U.S. President George W. Bush (in file photo) says he might seek new UN sanctions (CTK)
May 17, 2007 -- A senior Iranian official says Tehran has expanded work on its nuclear facility at Natanz in central Iran.
The Mehr news agency quoted Abdulreza Rahmani-Fazli, deputy secretary of the Supreme National Security Council, as saying more centrifuges have been installed at the plant.
Centrifuges can make fuel for nuclear power plants or produce material for atomic weapons.
Iran insists its nuclear plans are peaceful.
Western powers are concerned that Iran is trying to develop a nuclear bomb, and the International Atomic Energy Agency has said it does not have sufficient evidence to conclude that Tehran's nuclear program is not linked to weapons efforts.
U.S. President George W. Bush said on May 17 that the United States and Britain would seek new UN sanctions against Iran if it continued to resist calls for it to halt sensitive areas of its nuclear program.
Bush was speaking at the White House alongside outgoing British Prime Minister Tony Blair.
The U.S. president said Washington and London would "continue to make it clear that Iran with a nuclear weapon is not in the interest of peace in the world."
Bush has said in the past that he regards the prospect of Iran possessing nuclear weapons as "unacceptable."
The UN Security Council has approved two sets of sanctions in its effort to dissuade Tehran from pursuing some nuclear steps, including uranium enrichment.