Some of the world's most powerful oil executives are attending the St Petersburg economic forum, which kicked off Thursday.

The high-ranking guests are once again helping the organizers shrug off an otherwise meager turnout from Western entrepreneurs and bankers as Western sanctions over Russia's perceived role in the Ukraine conflict continue to bite and relations with the US and European governments remain frosty.

BP's latest review of world energy supplies estimated that Russian oil and gas reserves had jumped above 100 billion barrels for the first time, putting the country sixth in the global reserves league table. Reuters commented that "such an abundance makes it economically vital for major energy firms to maintain healthy ties with Moscow."

"We are in the long-term business, and this is why we are keen to maintain our commitment to Russia," said the head of France's Total, Patrick Puyanne.

German public opinion

Other investors have come to St Petersburg to make sure they don't lose the Russian market to competitors from Asia and other regions in the world.

The German public remains divided over the usefulness of Western sanctions against Russia. A fresh poll commissioned by energy company Wintershall sees 50 percent of respondents in favor of punitive measures, while 41 percent reject them.

Fifty percent of those polled described Russia as a very reliable energy supplier despite the Ukraine conflict, while 40 percent had misgivings about Russia's long-term reliability as a major energy partner.

hg/tko (AP, dpa)