Russia has started grain deliveries to Iran, sending 100,000 tons, Russia's food safety regulator, Rosselkhoznadzor, said.

RIA Novosti on Monday reported that Russian officials said in April that Russia was sending grain, equipment and construction materials to Iran in an oil-for-goods exchange, the first step in securing a foothold in a new market since the West imposed sanctions on Russia over Ukraine.

But traders, analysts and industry players questioned whether the long-heralded oil-for-goods barter deal had got under way, saying they had seen no signs of extra trade.

"Yes, deliveries already began a few days ago. At the moment 100,000 tonnes have been shipped," RIA quoted Alexei Alekseyenko, a Rosselkhodnadzor official, as saying.

Politically sensitive talks are now in their final stages on a deal to end a decades-old dispute between Iran and the United States, Britain, France, Russia, China and Germany on the nuclear program, which the West suspects has military aims.

Tehran says the program is for peaceful purposes.

Russia has acted quickly to cement ties with Iran after an interim deal was reached in April on curbing the Islamic republic's nuclear program in exchange for removing economic sanctions. The negotiating teams hope to reach a final accord by the end of this month.