The UN's nuclear watchdog says it has information indicating Iran has carried out tests "relevant to the development of a nuclear explosive device".

联合国原子能监察机构称，他们所掌握的信息显示伊朗已进行与“发展核爆装置有关的”试验。

In its latest report on Iran, the IAEA says the research includes computer models that could only be used to develop a nuclear bomb trigger.

Correspondents say this is the International Atomic Energy Agency's toughest report on Iran to date.

Tehran condemned¹ the findings as politically motivated.

"This report is unbalanced, unprofessional and prepared with political motivation and under political pressure by mostly the United States," said Ali Asghar Soltanieh, Iran's envoy² to the IAEA.

It was "a repetition（重复，副本） of old claims which were proven baseless by Iran in a precise 117-page response, " he added.

Iran says its nuclear programme is solely³ to generate civilian⁴ power.

The BBC's Bethany Bell, in Vienna, has examined the IAEA's latest quarterly report on Iran's nuclear programme.

She says the report gives detailed⁵ information - some of it new - suggesting that Iran conducted computer modelling of a kind that would only be relevant to a nuclear weapon.

The report, published on the Institute for Science and International Security website, notes that some of this research, conducted in 2008-09, is of "particular concern", our correspondent says.

"The application of such studies to anything other than a nuclear explosive is unclear to the agency," the report says.