“The U.S. is sending weapons to the opposition in Syria, which are being used against the government of that country,” Mr. Lavrov said, according to his official Russian-to-Persian translator. But hours later, Russia news services provided a revised translation of Mr. Lavrov’s remarks in which that accusation was deleted.

"We don’t supply Syria or anyone else with things that are used in fighting peaceful demonstrators, unlike the United States, which regularly supplies that region with such special equipment — one such shipment went to one of the Gulf countries recently, but for some reason the Americans consider this to be in order.”

Mr. Salehi went much further, asserting that weapons and foreign troops had been sent into Syria to aid the armed opposition to Mr. Assad. “They have some of their forces operating inside Syria,” Mr. Salehi said, without specifically naming the United States or any other country. “They say they want to prevent massacres but at the same time send weapons — these are double standards.”

The Russian and Iranian foreign ministers also expressed optimism over the June 18 nuclear talks in Moscow between Iran and world powers aimed at resolving Iran’s disputed nuclear program. “We believe the Iranian side is interested in the talks and seeking a solution for the dispute,” Mr. Lavrov said. Mr. Salehi said he was confident nuclear negotiations between Iran and world powers were heading in the right direction.

“Of course this is a complicated story,” he said of the nearly ten year long tensions over Iran’s nuclear program. “It takes patience and tolerance, but overall we are optimistic.”