An "attack on Iran by Western powers" could cause an unpredictable "chain reaction" throughout the region, Russia's Foreign Minister Sergei Lavrov has warned.

"It is impossible to list all the consequences [of an attack]. But I have no doubt that it would pour oil on the still smoldering fire of Sunni-Shia confrontation, which would lead to a chain reaction," Sergei Lavrov said in an annual address on Wednesday, as cited by RIA Novosti.

"As for how likely such a catastrophe is, you need to ask those who constantly mention this as an option," he added. Lavrov also said that Russia would "do everything" in its power to prevent an attack on Iran.

The Russian news agency RIA Novosti points out that although Israeli Defense Minister Ehud Barak said on Wednesday that Israel is "very far off" from taking the decision to strike Iran, Washington and Tel Aviv have refused to rule out military force against Tehran over suspicions that its nuclear program is aimed at the production of atomic weapons.

Iran, which recently began enriching uranium at an underground bunker, denies it is seeking nuclear arms and says its program is to provide peaceful civilian energy.

Lavrov also said that sanctions on Iranian oil exports being discussed by the European Union would "hurt" ordinary people and were more about stirring up unrest than nuclear non-proliferation.

"This has nothing to do with a desire to strengthen nuclear non-proliferation," he said. "It's aimed at stifling the Iranian economy and the population in the apparent hope of provoking discontent," he said, adding that sanctions would also prove "an obstacle" to the revival of a dialog between Iran and the six world powers involved in negotiations on its nuclear program.

Oil exports make up some 80 percent of Iran's foreign revenues and Tehran has threatened to close the Strait of Hormuz, the export route for one third of global seaborne traded oil, in response to sanctions. US Defense Secretary Leon Panetta has said such a move would provoke a response.

RIA Novosti points out that analysts are doubtful whether Russia has the military and economic clout to play a decisive role on Iran

"Russia has practically no real influence left in the Middle East. Iran cannot rely on Russia to defend it. The US and Israel are certainly not afraid of this. Russia will not definitely go to war over Iran," said analyst Sergei Demidenko of the Moscow-based Institute of Strategic Studies and Analysis.