Even as Russia and the West keep raising the stakes in their economic sanctions battle, the one commodity that could matter most — Russian natural gas — seems still to be off limits.

And that is all the more notable because long before Ukraine erupted as a geopolitical crisis, the European Union was aggressively pressing an antitrust case against the Russian state-controlled gas giant, Gazprom. If Europe has grounds to punish Moscow economically, the Gazprom antitrust case might seem to be a prime opportunity.

Gazprom is suspected of inflating prices and imposing unfair restrictions on gas distribution within Europe, which is heavily reliant on Russian natural gas.

As recently as last winter, Russia and the European Union’s competition commissioner, Joaquín Almunia, seemed on the verge of settling. But now the case appears to be languishing. And people close to the inquiry are uncertain whether it will be revived before the autumn, when Mr. Almunia is scheduled to leave office.

While that prospect is disappointing to small European Union countries like Lithuania that are particularly dependent on Gazprom for their energy needs, the lost momentum of the antitrust case seems to underscore a reality: So far the sanctions war may be more about symbolic actions than imposing far-reaching economic pain on either side.

A failure to press the Gazprom case “would mean that the commission is weak and not in a position to defend our own rules,” Jaroslav Neverovi, the energy minister of Lithuania, said in a telephone interview last week. He was referring to the European Commission, the E.U.’s administrative arm. Gazprom, Mr. Neverovi warned, could make “an attempt to get back to old practices” in future negotiations.

Lithuania is among six European Union member states dependent on Russia for all their gas. And, like Latvia and Slovakia, it relies on that source for more than a quarter of total energy needs. The other European Union countries wholly dependent on Russia for their natural gas are Bulgaria, Estonia and Finland, according to the European Commission.

Three years ago, Lithuania helped advance the Gazprom case by sending Mr. Almunia a formal complaint. Lithuania is also seeking compensation from Gazprom for what it contends were past pricing abuses at a separate arbitration proceeding in Stockholm.

As recently as last December, two months before Ukraine erupted, Mr. Almunia seemed eager to bring Gazprom to heel. At a meeting at the top of the glass-and-steel headquarters of the European Commission here, Gazprom’s representative was proposing concessions aimed at ending the antitrust investigation, which had badly irked the Kremlin.

The Gazprom executive, Alexander Medvedev, who was head of the company’s export division at the time, said then that it might even be possible to reach a settlement before the Winter Olympics got underway in February in the Russian city of Sochi. A person with direct knowledge of the meeting described the conversation, on condition of anonymity.

But Mr. Medvedev, accompanied by a Russian deputy energy minister, Anatoly Yanovsky, did not manage to settle the case before the Winter Games began. Subsequent talks on a deal between officials on both sides showed that they were still far apart on the allegations of overpricing.

And now, even as the Ukraine crisis has divided Russia and the West like nothing else since the Cold War, it is far from certain that Gazprom will face formal antitrust charges that could force the company to revise long-term contracts with countries like Lithuania.

Formal charges would also make it more likely that Gazprom would eventually be told to pay a fine — one that could theoretically run as high as 10 billion euros, or about $13.4 billion, although European Union antitrust penalties have never gone that high.

Antoine Colombani, a spokesman for Mr. Almunia, declined to comment on the December meeting or subsequent settlement talks. The antitrust “investigation is ongoing,” said Mr. Colombani. “We cannot anticipate the timing of decisions.”

The antitrust investigation began in September 2011 with surprise raids by European officials on Gazprom offices and those of several of its customers in Germany and across Central and Eastern Europe.

A year later Mr. Almunia opened a formal antitrust case asking three main questions: Was Gazprom blocking gas flows in some parts of Europe? Was the company thwarting its European customers’ efforts to diversify sources of supply? And was it imposing unfairly high charges by linking gas prices to those of oil, rather than basing prices on global natural gas market rates?

The case concentrated on Poland, the Czech Republic, Slovakia, Hungary, Bulgaria, Estonia, Latvia and Lithuania.

Analysts say one reason Mr. Almunia may have still not issued formal charges is that natural gas was conspicuously exempted in the sanctions that the European Union imposed on Russia last month.

The concern, they say, is that President Vladimir V. Putin of Russia could accuse the Europeans of ramping up an antitrust case as a rationale for extending the sanctions to natural gas. That could give the Russian leader, who has already told his government to follow the case with “very close attention,” another pretext to retaliate, perhaps by cutting supplies this winter.

Russian gas made up 39 percent of total European Union imports last year, up from 30 percent in 2010. About half those supplies are delivered through Ukraine, and previous flare-ups between Moscow and Kiev left some European cities shivering during midwinter in 2006 and 2009.

“Of course the Ukrainian crisis could have slowed down” the case, said Mario Mariniello, an expert in antitrust law at Bruegel, a research organization in Brussels.

But Mr. Mariniello said there were also legal reasons for Mr. Almunia’s hesitancy. “Proving the need to remove the link to the oil price is possibly the most challenging part of the case to resolve,” he said.

Gazprom was willing to resolve antitrust disputes with Europe a decade ago when it agreed to end restrictions in Western Europe that had prevented its customers in Italy, Austria and Germany from reselling Russian gas to other countries.

But the current case is a challenge to the way Gazprom links its gas prices to oil. That is a hugely sensitive issue for Mr. Putin and Russia, where a significant chunk of the national budget depends on the company’s energy export earnings.

Oil-linked pricing in Europe goes back decades to the development of gas fields in countries like the Netherlands. Gas was pegged to the price of oil, which gas was replacing for uses like heating.

But linked pricing began breaking down in Western Europe with deregulation of energy markets and with the availability of new supplies like liquefied natural gas, or L.N.G. But pricing still can be opaque, even in Western Europe, where a complete break of the oil-gas price link has proved difficult for big buyers in countries including Italy.

Energy experts said Mr. Almunia would be on firm legal ground in demanding that Gazprom rid contracts of clauses that limit Eastern and Central European countries from shipping Russian gas to other destinations within the European Union. But many say that Mr. Almunia may have less standing to challenge Gazprom’s pricing practices.

“For the Baltic States and Poland I think the commission is on difficult ground,” said Jonathan Stern, the chairman of a natural gas research program at the Oxford Institute for Energy Studies. He said the only viable alternative source of supply for those countries was L.N.G., which usually comes by ship from countries like Qatar and Norway and still is generally more costly than Russian gas carried by pipeline.

“It’s very unlikely that either the Poles or the Lithuanians or anyone in the Baltics currently and historically could have obtained gas at a cheaper price than the Russians are selling it to them,” Mr. Stern said. “Politicians and people high up in the commission say the fact that prices charged to the Baltic States are higher than the prices charged to Germany proves those prices are anticompetitive. But that is not proof.”

The countries involved in the antitrust inquiry still lack cheaper energy alternatives, Mr. Stern said. “There’s no backup at the moment,” he said, and “who knows what will happen to L.N.G. prices in the next couple of years?”

But proponents of bringing formal charges against Gazprom say that energy alternatives should be available soon, as countries including Lithuania and Poland begin operating planned seaport terminals that could give them leverage to negotiate lower prices on Russian supplies.

They also say geopolitics — not just lower gas prices — should be a consideration, in encouraging Ukraine to more closely embrace Europe as it turns away from Russia.

“If we send a message that all parties that are participating in the European gas sector are treated equally, and they are subject to the same set of requirements and rules,” said Mr. Neverovi, the Lithuanian minister, “then Ukraine might implement European law, realizing it is seriously treated and protected by the E.U.”

Without that message, Russian and Ukrainian energy companies would probably continue to “divide the market and manipulate the price and use all the tricks” that Europe is trying to eradicate, he said.

Stanley Reed