WASHINGTON - THE United States believes Iran has enough fissile material to build a nuclear bomb, top military officer Admiral Mike Mullen said on Sunday, marking the first time Washington has made such an assessment.

'We think they do, quite frankly,' Adm Mullen told CNN when asked if Iran had enough nuclear material to manufacture an atomic bomb.

'And Iran having a nuclear weapon, I've believed for a long time, is a very, very bad outcome for the region and for the world,' said Adm Mullen, the chairman of the US Joint Chiefs of Staff.

While the United States and European allies have expressed concern previously that Iran could soon have sufficient enriched uranium to manufacture a nuclear weapon, Adm Mullen's more definitive comments went a step further.

The admiral's remarks came in the wake of a report by the UN nuclear watchdog, the International Atomic Energy Agency (IAEA), that said Teheran had made major strides in its uranium enrichment work.

Citing the report, some analysts say Iran may have sufficient material to make a nuclear bomb or may be close to that point.

According to the IAEA, Teheran now has 1,010 kilogrammes of low-enriched uranium hexafluoride from its enrichment activities at a plant at Natanz.

That 'is sufficient for a nuclear weapons breakout capability', according to David Albright, president of the Washington-based Institute for Science and International Security and an expert on Iran's nuclear programme.

A breakout capability is defined as securing enough low-enriched uranium, used for nuclear fuel, to turn into highly enriched uranium needed for nuclear weapons.

Iran denies its atomic work is designed to build a nuclear arsenal and says it wants to develop nuclear technology to generate electricity for a growing population.

The White House declined to comment on Sunday when asked about Mullen's assertion. -- AFP