Senior diplomats from six world powers are to meet this week to discuss stalled efforts to impose new sanctions on Iran over its nuclear program, U.S. officials said Tuesday.

Thursday''s meeting in Paris will bring together high-level foreign ministry officials from the five permanent members of the U.N. Security Council — Britain, China, France, Russia and the United States — and Germany, the officials said. The U.S. will be represented by Undersecretary of State for Political Affairs William Burns, they said.

Burns is currently in Moscow for talks with senior Russian officials on Iran and other matters, including Russia''s war with Georgia and U.S. plans for a missile shield in Europe that have seriously damaged ties between the former Cold War foes, the officials said.

Burns, the third-ranking official in the State Department, is the most senior official to visit Russia since the war in Georgia in August, although Secretary of State Condoleezza Rice has met with Russia Foreign Minister Sergey Lavrov twice since then, most recently over the weekend in Egypt.

The officials spoke on condition of anonymity because neither Burns'' travel nor the meeting in Paris has been formally announced.

In its final months, the administration has been hitting Iran, particularly its banking and finance sectors, with a host of new U.S. sanctions over its refusal to halt suspect nuclear activity like uranium enrichment that Washington and its allies say are aimed at developing atomic weapons. Iran says the work is to produce power, not bombs.