EU regulators aiming to build a strong energy union to weaken Russia's market power are planning to introduce a law that will require each member state to seek EU commission approval before concluding new gas contracts, German daily Sueddeutsche Zeitung said in an advance copy of its Tuesday edition.

This will also apply to companies like German utility E.ON or BASF's oil and gas unit Wintershall , the paper said, citing a draft law.

It would mean that in the future companies must get approval from Brussels before they can enter into agreements with Russian gas suppliers.

For countries that are particularly dependent on one supplier, the draft provides for establishing purchasing groups, Sueddeutsche Zeitung said.

The European Union aims to reduce reliance on imported fossil fuel from nations such as Russia, and to press ahead with completion of a single energy market, a goal that has proved elusive for decades.

Russia's annexation of Ukraine's Crimea region last year underscored the need for Brussels to do more to safeguard the EU's energy supply. Europe relies on Russia for about a third of its gas, almost half of which is piped via Ukraine.

While EU deliveries were not disrupted after Russia cut off Ukraine's supply, ongoing tensions with Moscow, including its plans to divert piped supplies away from Ukraine, have spurred talks on better EU cooperation and the need for alternative supplies.