Russia said Wednesday it is "very concerned" by new EU sanctions against Iran, which it claimed will work against talks on Tehran's contested nuclear programme.

"We are very concerned by the European Union's adoption on October 15 of a new series of unilateral sanctions against Iran," the foreign ministry said.

"We repeat: We do not consider unilateral sanctions, introduced by states or groups of states circumventing the UN Security Council, as legitimate instruments of international policy," the ministry said.

The EU sanctions "undermine the resumption of negotiations with Iran, which in our opinion have registered progress," the ministry said, describing the measures as "unacceptable".

The six powers of the United States, Russia, China, Britain, France and Germany have been holding recent negotiations with Iran in a bid to halt its uranium enrichment work.

But Western officials say that Iran is stonewalling in the negotiations.

"We are again forced to establish that the inconsiderate gestures of the European Union countries strike a sensitive blow to the unity of the group of six international negotiators," the foreign ministry said.

It said Russia will continue to work hard to organise as quickly as possible the next round of talks between the six powers and Iran.

European Union foreign ministers on Monday agreed a slew of tough new financial and trade sanctions against Iran aimed at forcing a breakthrough in the talks on Tehran's nuclear programme.