Iran has conducted research into nuclear fusion, an Iranian nuclear official was reported as saying Monday by state television.It was the first time the country declared such a development."Iranian nuclear scientists are competing with the advanced world in the field of producing nuclear energy through fusion," the official, Sadat Hosseini, was reported as saying by the television.Nuclear fusion is the process by which multiple nuclei join together to form a heavier nucleus. It is accompanied by the release or absorption of energy depending on the masses of the nuclei involved.Hosseini, who runs the technical department at the Nuclear Research Center of Iran's Atomic Energy Organization, added: "The first research of nuclear fusion in Iran was done five years ago."It was not immediately clear why Iran had decided to announce the research only now, but the move seemed to be part of the country's defiance of world calls for it to limit its nuclear program to activities that could not be used for making weapons. Nuclear fusion is employed by certain kinds of atomic bomb.The five major powers on the UN Security Council - the United States, Russia, China, Britain and France - and Germany are scheduled to meet in London on Wednesday to discuss a plan intended to persuade Iran to stop enriching uranium - a process that produces fuel for nuclear generators of electricity or material for bombs.Foreign ministers of the six countries appeared to have narrowed their differences on a package of rewards or sanctions that are to be put before Iran.The US and some of its allies accuse Iran of using a civilian nuclear program as a cover to produce nuclear weapons. Iran denies this, saying its nuclear program is merely to generate electricity.The Security Council gave Iran until the end of April to suspend all activities linked to enrichment. But Iran ignored the demand and announced last month that it had for the first time successfully enriched uranium and was performing research on advanced centrifuges to enable it to accelerate its enrichment.Also Monday, government spokesman Gholam Hossein Elham said reiterated that Iran had no plan to stop enrichment or to transfer it to Russian soil - as Moscow has proposed."There has been no discussion about Iran giving up enrichment and continuing it on Russian soil," Elham told reporters at a weekly briefing.