WASHINGTON - A confidential analysis by staff of the U.N. nuclear watchdog has concluded that Iran has acquired sufficient information to be able to design and produce an atom bomb, The New York Times reported on Saturday.

The Times report was posted on its website hours after Mohamed ElBaradei, head of the International Atomic Energy Agency, arrived in Tehran for talks on a timetable for inspectors to visit a newly disclosed unfinished nuclear enrichment plant.

Iran, which rejects Western charges that it is seeking to build nuclear weapons, held talks with six world powers in Geneva on Thursday. Western officials said that in the talks, Iran had agreed in principle to ship out most of its enriched uranium for reprocessing in Russia and France.

The analysis, according to the Times, says the IAEA assesses that Iran has sufficient information to be able to design and produce a workable implosion nuclear device based on highly enriched uranium.

The Times said unnamed senior European officials had described the document's conclusions to the paper. It said the report was written earlier this year and had since been revised, and quoted one official as saying the text was not ready for publication as an official document.

It said the report, titled Possible Military Dimensions of Iran's Nuclear Program, described a complex program run by Iran's Defense Ministry aimed at the development of a nuclear payload to be delivered using the Shahab 3 missile system.

The report said the program apparently started in 2002. It suggested the Iranians have done a wide array of research and testing to perfect nuclear arms, like making high-voltage detonators, firing test explosives and designing warheads, the Times said, but it did not say how much progress they made.

The agency's tentative analysis also says that Iran 'most likely' obtained the needed information for designing and building an implosion bomb 'from external sources' and then adapted the information to its own needs, the Times said.

The paper said a dispute had erupted in recent months over the report between the IAEA's senior staff and ElBaradei, the agency's outgoing director who opposes adopting a confrontational strategy with Iran.

In recent weeks, there have been leaks about the internal report, perhaps intended to press Dr. ElBaradei into releasing it, the Times said.

(Writing by Mohammad Zargham; Editing by Peter Cooney)