Stockholm  - Questions over how Russia plans to join the World Trade Organization (WTO) overshadowed the opening of a summit with the European Union in Stockholm on Wednesday.

Russia announced in June that it was planning to join a customs union with Belarus and Kazakhstan as of January, throwing trade negotiations with the WTO and the EU into confusion because it is now not clear if the three countries seek to join the WTO individually, or as a bloc.

"The lack of clarity over Russia's intentions concerning its WTO membership implies a considerable uncertainty" both for the accession talks and for talks on a wide-ranging strategic treaty between Russia and the EU, Sweden's Foreign Minister Carl Bildt wrote on his blog just ahead of the summit.

Sweden currently holds the EU's rotating presidency.

EU officials say that Russia's plan to set up a customs union with its one-time Soviet vassals calls into question the foundations of WTO accession talks and EU-Russia trade negotiations by potentially changing the entire basis of the talks.

Ahead of Wednesday's summit, Russia's ambassador to the EU, Vladimir Chizhov, said that all three countries wanted to join the WTO, but that it was not yet clear whether they would do so as a group, in parallel, or separately.

"It is well-known that the three countries are at different stages of negotiation with the WTO. That needs to be rectified, not by slowing Russia's own pace but by speeding up the process with the other two," Chizhov said.

Despite the concerns over trade issues, however, Russian President Dmitry Medvedev and Swedish premier Fredrik Reinfeldt were at pains to stress the positive aspects of the two sides' relationship on issues such as climate change after an informal dinner on Tuesday evening.

The EU is keen to enlist Russian support for an ambitious deal to fight climate change at United Nations talks in Copenhagen in December.

"Our countries are among the few in the world that have decreased their greenhouse gas emissions since 1990," Reinfeldt pointed out.

Medvedev said that "our countries are among the most advanced in terms of commitments (to address climate change) and the desire to move ahead" in Copenhagen.

Both leaders also stressed the need for Russia to crack down on corruption so that Western companies would feel comfortable investing there.

"We need sustainable and predictable business conditions for Swedish businesses who want to work in Russia," Reinfeldt said.

But they also stressed that corruption is not a uniquely Russian phenomenon.

"Corruption is a universal phenomenon ... These processes should be controlled and corruption should be suppressed," Medvedev said.

They were also set to discuss energy security and international hot spots such as Iran and Afghanistan. (dpa)