Ukraine is ready to start talks with Russia, mediated by the European Union, over the so-called 'summer package' of agreements on natural gas supplies to replace the current 'winter' package.

Speaking at a conference organized by a European political centre in Brussels on Tuesday, Naftogaz Ukrainy chief executive Andriy Kobolev said he would not try to predict the course of such negotiations.

"Previous experience shows that it took us six months," he said.

The talks will depend primarily on the Russian position, he said.

"Commercially wisely, we would expect Gazprom to offer us an honest price," Kobolev said.

The start date of the next negotiations has yet to be set, he said.

"Our understanding is that our Russian colleagues will not be prepared to start the talks before January," the Naftogaz chief said.

It was reported that the trilateral gas talks which Ukraine, Russia and the European Union began in the spring of 2014, ended on October 30 with the signing in Brussels of the so-called "winter package" setting the conditions for natural gas supplies until the end of March 2015.

Meanwhile, a Stockholm arbitration court is hearing lawsuits filed by Gazprom and Naftogaz Ukrainy against each other over gas contracts signed in 2009. Kyiv is not expecting these disputes to be resolved before the fall of 2015.