Khan, revered at home as the father of the country's nuclear bomb, has been accused of leaking atomic weapons secrets to Libya, Iran and North Korea.

"My brothers and sisters, I have chosen to appear before you to offer my deepest regrets and unqualified apologies to a traumatised nation," Khan said on Pakistan Television, speaking in English. "I also wish to clarify that there was never ever any kind of authorisation for these activities by the government."

Khan also asked for clemency from President Pervez Musharraf, the government said.

Musharraf is believed to be considering whether to prosecute the scientist, revered at home for developing Pakistan's atomic bomb.

"Dr A.Q. Khan submitted before the President that he accepts full responsibility for all the proliferation activities, which were conducted by him during the period in which he was at the helm of affairs of Khan Research Laboratories," the government said in a statement.

Khan headed KRL, the country's main nuclear research organisation, until 2001.

"Dr Khan has submitted his mercy petition to the president and requested for clemency, in view of his services to national security," the statement added.

Intelligence sources said Khan had called the meeting in a last-ditch bid to strike a deal and avoid prosecution.

Many Pakistanis and Western diplomats feel that Khan has been treated as a scapegoat, and that he could not have acted as he did without the knowledge of senior military officials.

Pakistan's military has strongly denied remarks attributed to a friend of Khan saying the scientist had told investigators Musharraf was among those who knew he had given nuclear know-how to North Korea in the 1990s.

In his first public remarks since an investigation into the nuclear leaks by Pakistan was launched over two months ago, Khan told state-run Pakistan Television he had requested the meeting.

"The president was extremely kind and understanding. We discussed this ongoing affair, the international campaign against Pakistan about nuclear matters," he said.

"I explained to him all the things. I gave him the background, what is happening, what had happened and he appreciated the frankness with which I gave him the details."