Washington, April 1 (IANS) An Iranian nuclear scientist, who has been missing since June last from Saudi Arabia, has defected to the US and is helping in CIA's operation against Tehran's nuclear programme, a media report said.

Shahram Amiri, an award-winning nuclear physicist, has been settled in the US, ABC News reported quoting people briefed on the operation by intelligence officials.

The officials were said to have termed the defection of the scientist, 'an intelligence coup' in the continuing CIA operation to spy on and undermine Iran's nuclear programme.

However, a CIA's spokesperson declined to comment.

According to the people briefed on the intelligence operation, Amiri's disappearance was part of a long-planned CIA operation to get him to defect. The CIA reportedly approached the scientist in Iran through an intermediary who made an offer of resettlement on behalf of the US.

Amiri has been extensively debriefed since his defection by the CIA, according to the people briefed on the situation. They said, he helped to confirm US intelligence assessments about the Iranian nuclear programme.

In its declassified annual report to Congress, the CIA said, 'Iran is keeping open the option to develop nuclear weapons though we do not know whether Tehran eventually will decide to produce nuclear weapons.'

Amiri, in his early 30s, went missing after he visited Saudi Arabia on a pilgrimage, according to the Iranian government, which also accused the US of 'kidnapping' the scientist. Amiri had worked at the Qom facility prior to his defection.

'The significance of the coup will depend on how much the scientist knew in the compartmentalised Iranian nuclear programme,' said former White House counter-terrorism official Richard Clarke, an ABC News consultant. 'Just taking one scientist out of the programme will not really disrupt it.'