BERLIN Germany's BND foreign intelligence agency said on Wednesday that Iran was probably years away from being able to produce and test an atomic bomb.
Earlier, German weekly Stern reported that BND experts believed Iran had mastered the enrichment technology necessary to make a bomb and had enough centrifuges to make weaponized uranium.
The magazine quoted one unnamed expert at the agency as saying: "If they wanted to, they could detonate an atomic bomb in half a year's time."
A BND spokesman said the agency's forecast was that it would take Iran several years to reach that point, although there was much uncertainty surrounding that view and that a shorter time period was also possible.
"The BND assumes that under ideal conditions, Iran would be capable of producing an atomic bomb in a laboratory setting in under five years," the spokesman said.
He made clear, however, that it would take Iran far longer to get to the point where it was in a position to produce a deliverable atomic warhead.
Iran says its nuclear program is for electricity generation to help it export more of its oil and gas, but Western countries suspect it of trying to make a nuclear bomb.
The U.N. Security Council has imposed three sets of sanctions on Tehran for defying its demands to suspend uranium enrichment.
Some analysts say Iran may be close to having the required material for producing a bomb, but most say the weaponization process would then take one to two years due to technical and political hurdles.
Mark Fitzpatrick, senior non-proliferation fellow at London's International Institute for Strategic Studies, said six months was an "absolutely a worst-case analysis."
He said that while it might be plausible in theory that Iran could further enrich uranium in a large enough quantity for a bomb as well as restarting the weapon design work it halted in 2003, these actions would not go unnoticed.
He said there was also disagreement as to how advanced the weapons design work was.
"If Iran were to go for broke and produce a nuclear weapon in this manner, it would have to expel International Atomic Energy Agency inspectors and the world would know," he said.
Until now there have been no indications of any such covert diversion, a point made by the IAEA's incoming director-general shortly after his election earlier this month.
Current IAEA chief Mohamed ElBaradei has said it is his "gut feeling" that Iran is seeking at least the capability to build nuclear weapons, in order to protect itself from perceived regional and U.S. threats.
The Islamic Republic has largely rebuffed efforts by U.S. President Barack Obama for dialogue and has sharpened its rhetoric against the West following its disputed presidential election in June.
(Reporting by Noah Barkin and Sylvia Westall in Vienna; Editing by Mark Trevelyan)