Pakistan said Thursday that nuclear scientist Abdul Qadeer Khan had no access to atomic facilities after Washington expressed concern he could become a renewed proliferation threat.

A Pakistani court declared Khan a free man last week, five years after the man reputed to be the father of Pakistan's nuclear bomb was effectively put under house arrest for allegedly operating a proliferation network.

"Doctor Khan has no access to strategic facilities -- he has nothing to do with the nuclear programme," foreign office spokesman Abdul Basit told reporters in Islamabad.

The 72-year-old Khan, revered by many Pakistanis as a national hero, was effectively put under house arrest in February 2004 when he confessed on television to leaking nuclear secrets to Iran, Libya and North Korea.

Then president Pervez Musharraf pardoned Khan in 2004, but he was kept at his Islamabad residence, guarded by troops and intelligence agents.

"Our position on the issue is very clear and I think the US understands and accepts it," Basit said.

A US official said Monday that Washington wanted more than just "solid" assurances from Pakistan that Khan will not be a threat following his release.