London ? The U.S., Britain, France, Germany, China and Russia will confer today in London to assess Iran’s defiant refusal to suspend uranium enrichment. They are expected to refer the nuclear case to the U.N. Security Council for talks next week on possible sanctions, diplomats said Thursday.

Russia’s foreign minister, however, said he believes it is too soon to impose sanctions on Iran and that further efforts are needed to push Tehran to negotiate.

To avoid alienating the Russians and the Chinese, any sanctions are likely to be relatively mild, including embargoes on missile and nuclear technology, and possible travel bans and other penalties on Iranian officials involved in their country’s nuclear program.

Iranian President Mahmoud Ahmadinejad reiterated Thursday that his country would not be frightened by threats to impose sanctions.

“Those who threaten Iran by sanctions and embargo should know that this nation lived under the hardest situation in the past 27 years and achieved nuclear technology. This nation will not be frightened by the threats,” state-run television quoted Ahmadinejad as saying.

Iran insists that its enrichment of uranium is purely for peaceful purposes to be used for nuclear energy. But the United States and many European nations believe Iran wants to enrich uranium to produce nuclear weapons.

Secretary of State Condoleezza Rice, British Foreign Secretary Margaret Beckett and French Foreign Minister Philippe Douste-Blazy were to attend the 5 p.m. meeting in London. Germany, Russia and China also will send high-level officials to the talks. Of the six nations, only Germany is not a permanent member of the Security Council.

The officials were likely to confirm that the European-Iranian talks aimed at persuading Tehran to suspend its enrichment program are at a standstill, a senior Security Council diplomat said. They also probably will issue a statement referring the case back to the council and listing the principles on which they agree, according to the diplomat, who spoke on condition of anonymity because talks were still taking place.

Britain’s U.N. Ambassador Emyr Jones Parry said he expects “the Iran dossier” to return to the council “in the course of next week.” He said Britain “will be discussing with its partners and with members of the council the basis for action by the council to adopt measures under Article 41 against Iran.”

Article 41 authorizes the Security Council to impose sanctions that do not involve the use of armed forces – such as issuing economic penalties, breaking diplomatic relations or banning air travel.