The son of Al-Qaida leader Osama bin Laden has been killed by a US missile attack in Pakistan, US National Public Radio has reported.

Saad bin Laden was believed killed in a missile strike from a US drone earlier this year, intelligence officials told the broadcaster on Wednesday.

An unnamed intelligence source said US spy agencies were "80 to 85 per cent" sure the younger bin Laden had been killed, the report said.

Though he was an Al-Qaida member, he was not believed to be a significant part of the organisation.