Iran tested advanced nuclear warhead - report

LONDON (Reuters) - The U.N. nuclear watchdog has asked Iran to explain evidence suggesting the Islamic Republic's scientists have experimented with an advanced nuclear warhead design, the Guardian reported in its Friday edition.

The newspaper, citing what it describes as "previously unpublished documentation" from an International Atomic Energy Agency compiled dossier, said Iranian scientists may have tested high-explosive components of a "two-point implosion" device.

The IAEA said in September it has no proof Iran has or once had a covert atomic bomb program.

The Vienna-based IAEA was not immediately available for comment on Thursday.

Iran's Foreign Ministry and the Atomic Energy Organisation of Iran (AEOI) were also unavailable for comment when contacted by Reuters.

The IAEA statement in September followed reports from the Associated Press quoting what it called a classified IAEA document saying agency experts agreed Iran now had the means to build atomic bombs and was heading towards developing a missile system able to carry a nuclear warhead.

The Guardian report said that even the existence of two-point implosion nuclear warhead technology is officially secret in both the United States and Britain.

The technology allows for the production of smaller and simpler warheads, making it easier to put a warhead on a missile, the newspaper said.

Extracts of the dossier have been published before, but it was not known the dossier included documentation of such a sophisticated warhead, the newspaper said.