"We believe the common action (over Iran) must be continued, but the United States have taken a unilateral decision affecting all parties, which limits activities in Iran not only of American companies but of all companies," Lavrov said during a visit to Poland.

"A unilateral step such as this will certainly not help efforts to draw up a collective response (to Tehran), but we will see what we can do tomorrow in London," Lavrov said.

The so-called P5-plus-1 group, made up of the five permanent members of the UN Security Council -- Britain, China, France, Russia, and the United States -- and Germany, is due to meet in London Friday to try to reach compromise deal over Iran's nuclear programme, the Russian foreign ministry announced earlier.

"We will take as our lead the agreements that have already been struck by the Six, and on the basis of which (EU foreign policy chief) Javier Solana is continuing his efforts," Lavrov said.

"We are very worried by the fact that there has not been, up to now, a satisfactory response from Tehran," he said.

"We will continue with the diplomatic effort, even though some are in favour of sanctions as of now," the Russian foreign minister added.

"We have already said that sanctions are extreme measures. We will discuss the full range of measures available to the international community" to try to resolve the crisis with Iran, he said.

"We will see what other possibilities exist to continue with multi-party diplomatic efforts," he said.

Russia has strong economic interests in Iran, including a project to build a nuclear power station.

Moscow and Tehran signed an agreement last week for the Russian-built Bushehr nuclear power station to come online in September next year.

The deal reaffirmed Russia's commitment to the controversial project, estimated to be worth some one billion euros, despite strong US objections to the project.

During a trip to Los Angeles last week, Lavrov said that Russia would not deal with the Iranian problem by joining other countries in issuing an ultimatum over its nuclear program, RIA Novosti news agency reported.

"We cannot endorse an ultimatum that will force everyone into a dead end and produce a new crisis in an already destabilized region," he said, insisting then, too, that compromise was the only way forward.

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