By Alexei Anishchuk
MOSCOW, Jan 18 (Reuters) - Russia warned on Wednesday that an attack on Iran would cause a catastrophe and said U.S. and European Union sanctions against Tehran were aimed at triggering popular discontent by "strangling" the economy.
Foreign Minister Sergei Lavrov said that Western sanctions against Iran and talk of a potential attack undermine efforts to revive negotiations aimed at ensuring it does not develop nuclear weapons.
Speaking at his annual news conference, Lavrov said Western nations must focus on efforts to revive long-dormant talks between global powers and Tehran "and not on sanctions, let alone threats to use force".
"I have no doubt that it would pour fuel on a fire which is already smouldering, the hidden smouldering fire of Sunni-Shi'ite confrontation, and beyond that (cause) a chain reaction - I don't know where it would stop," he said of an attack.
"On the chances of whether this catastrophe will happen or not you should ask those who repeatedly talk about this," Lavrov said.
Israel has often said it could strike Iran to stop it developing nuclear weapons, and tension has increased following a Iranian threat to block the Strait of Hormuz, a crucial oil shipping lane, if sanctions prevent it exporting oil.
Lavrov emphasised Russia's opposition to further U.N. Security Council or Western sanctions against Iran over its nuclear programme, which the United States and its European allies fear is aimed at producing weapons.
"All imaginable sanctions that could influence Iran's conduct in the nuclear sphere ... have been exhausted," Lavrov said.
Additional sanctions "are aimed at causing a strangling effect on the Iranian economy and the situation of the Iranian people, probably in the hope of provoking discontent," he said. (Reporting by Alexei Anishchuk, Writing by Thomas Grove and Steve Gutterman)