Russia's senior negotiator at Iran nuclear talks says European foreign ministers are set to join the talks over the weekend, but his minister does not plan to come.

The comments, by Sergey Ryabkov, suggest that the negotiations have a ways to go before reaching agreement on a preliminary deal ahead of an end-of-March deadline. All ministers of the six powers at the negotiating table would be expected to show up in case of a pending pact.

Ryabkov told The Associated Press Friday that Russian Foreign Minister Sergey Lavrov's absence is not "political." He says that — unlike Moscow — some European nations have particular "concerns" at this point of the talks.

Iran is negotiating with the United States, Russia, China, Britain, France and Germany.