"This is a shift from the technical level to gauge the temperature at a high political level to see if the outstanding issues can be resolved soon," a diplomat familiar with preparations for the talks said. "They need to see if the negotiations have reached the end-game," he said.

EU Trade Commissioner Catherine Ashton, US Trade Representative Ron Kirk and Russian Economy Minister Elvira Nabiullina will meet on the sidelines of the St. Petersburg Economic Forum, which starts on June 4.

Russia, which has been trying for more than a decade to join the 153-member WTO, is the largest economy to remain outside the organization.

"A great deal of work remains, particularly by the Russian Federation, in order to take the accession process forward to the finish line," said Nefeterius McPherson, a spokeswoman for US Trade Representative Ron Kirk.