MOSCOW — Russia expressed regret and concern Tuesday about Iran's launch of uranium enrichment up to 20 percent at an underground facility, but urged all parties involved in the nuclear standoff with Tehran to avoid hasty moves.

The Russian Foreign Ministry's statement mixed cautious criticism of Iran, an important trading partner, with a call for more talks — a fine line Moscow has walked in the past.

The Foreign Ministry said in a statement that the launch of the work at the facility near Iran's holy city of Qom demonstrated that Tehran was continuing to ignore international concerns about its nuclear program. It added, however, that Iran had notified the International Atomic Energy Agency in due time of its plans for the bunker.

"We hope that Tehran will listen to our opinion about the need for a further close cooperation with the agency and a quick start of serious six-way talks on the Iranian nuclear program without any preconditions," it said.

The IAEA confirmed Monday that Iran has begun enriching uranium up to 20 percent at an underground bunker at the Fordo site near Qom. Even though Tehran announced the move months ago, it increased international fears that Iran is determined to move closer to the ability to make nuclear warheads despite its assurances that its program is aimed exclusively at producing reactor fuel.

The Russian Foreign Ministry, meanwhile, said Moscow was urging all parties involved in the Iranian nuclear standoff to avoid "ill-considered and abrupt moves," which could undermine prospects for talks with Iran.