Iran (search) is circumventing international export bans on sensitive dual-use materials by smuggling graphite and a graphite compound that can be used to make conventional and nuclear weapons, an Iranian dissident and a senior diplomat said Friday.

Graphite has many peaceful uses, including steel manufacture, but also can be used as a casing for molten weapons-grade uranium (search) to fit it to nuclear warheads or to shield the cones of conventional missiles from heat.

With most countries adhering to international agreements banning the sale of such "dual-use" materials to Tehran (search), Iran has been forced to buy it on the black market, Iranian exile Alireza Jafarzadeh (search) told The Associated Press — allegations confirmed by a senior diplomat familiar with Iran's covert nuclear activities.

"It is not clear how much governments are involved," Jafarzadeh said later in an interview with Associated Press Television News, adding that he believes Iran is "using front companies to deceive other companies, other entities in foreign countries, and they wouldn't know what the destination would be."

Phone calls to Iranian diplomats seeking comment were not answered.

While with the National Coalition of Resistance of Iran (search), Jafarzadeh disclosed information about two hidden nuclear sites in Iran in 2002 that helped uncover nearly two decades of covert Iranian atomic activity — and sparked present fears Tehran wants to build the bomb.

Much of the equipment — including centrifuges for uranium enrichment and other technology with possible weapons applications — was acquired on the nuclear black market.

Those implicated include Henk Slebos, a Dutch businessman who is awaiting trial in the Netherlands on charges of importing banned material — including 100 pieces of graphite — as part of disgraced Pakistani nuclear scientist Abdul Qadeer Khan's clandestine smuggling network.

Jafarzadeh, whose organization was banned in the United States for alleged terrorist activity and who now runs the Washington-based Strategic Policy Consulting think tank, said Iran was additionally smuggling and trying to manufacture a graphite-based substance called ceramic matrix composite. The highly heat resistance compound is also used in missile technology.

He said he learned this from sources of information within Iran.

The diplomat, who requested anonymity because of the sensitivity of his position, said Iran also may be interested in acquiring specially heat-resistant "nuclear-grade graphite" that can be used as moderators to slow down the fission process in reactors generating energy.

While Iran does not now have reactors using such moderators, it insists it has the future right to all aspects of peaceful nuclear technology.

Neither Jafarzadeh nor the diplomat could say how much graphite Iran had imported and over what period of time.

But the diplomat said a graphite-moderated nuclear plant would require a "huge amount" of graphite — as many as 1,000 tons for a 250-megawatt reactor.

Crucibles to hold molten uranium metal would need much less graphite — no more than about 2.2 pounds per nuclear weapon, the diplomat said. He said investigations by the Vienna-based International Atomic Energy Agency revealed laboratory experiments by Iran aimed at making nuclear-grade graphite, which later were abandoned.

Domestically manufactured Iranian conventional missiles would require dozens of pounds of graphite per missile cone, he said.

Jafarzadeh also said a plant now being built near the central town of Ardekan for what Iranian officials say is steel manufacturing will actually be a cover for mastering graphite technology.

The revelations came as Iran's top nuclear negotiators prepared to meet early next week with the foreign ministers of France, Britain and Germany, acting on behalf of the 25-nation European Union, for what could be a last-ditch attempt to convince Tehran to agree to a long-term freeze of uranium enrichment activities.

French Foreign Minister Michel Barnier said Friday the talks were "very fragile." He said the talks range over issues including economic, technical and commercial cooperation, Iran's wish to join the World Trade Organization, and political dialogue.

The United States wants U.N. Security Council action against Iran for what it says are nuclear weapons ambitions, and the Europeans have threatened to support such U.S. calls if it resumes enrichment programs. Iran says those programs are needed to generate power, but Washington labels them as part of plans to make weapons-grade material.