For the first time since the release last week of convicted Lockerbie bomber Abdel Basset Ali al-Megrahi from a Scottish prison and his return to Libya, Britain's prime minister has addressed the issue publicly.

Opposition politicians say Prime Minister Gordon Brown's silence on the release of the only man convicted of bombing Pan Am Flight 103 nearly 21 years ago shows poor leadership and a lack of courage.

After returning from summer vacation on Tuesday, Mr. Brown said he earlier told Libyan leader Moammar Gadhafi that the British government would played no part in any action regarding Megrahi's possible early release.

"When I met [Libyan leader] Colonel [Moammar] Gadhafi over the summer, I made it absolutely clear to him that we had no role in making the decision about Megrahi's future," he said.  "Because it was a quasi-judicial matter, because it was a matter legislated for by the Scottish Parliament and not by us, it was a matter over which we could not interfere and had no control over the final outcome."

But earlier, Mr. Gadhafi had thanked Mr. Brown for what he called his "influence" in allowing Megrahi to return to Libya.

The convicted bomber is suffering from terminal cancer.  Authorities say his release was based on compassionate grounds.  Megrahi was serving a life sentence for the 1988 jetliner bombing over Scotland that killed 270 people, most of whom were Americans.

His release has generated a wave of criticism in the United States - from leading politicians and the head of the Joint Chiefs of Staff to the director of the FBI - all condemning the transfer of Megrahi  to Libya.  Many family members of the American victims say they feel let down and several Internet Web sites are urging Americans to boycott British and Scottish goods and tourism.

Asked by reporters whether he felt the release could undermine relations between Britain and the United States, Prime Minister Brown said he has reassured U.S. leaders that Britain remains a vital partner in the war on terror.

"I made it absolutely clear that whatever the decision that is made on a quasi-judicial basis by the Scottish Parliament, our determination to fight terrorism is clear," he added.  "It is shown in all the action we have taken since September the 11th.  It is shown in the support we have given in Iraq and Afghanistan to dealing with problems, where terrorism rears its ugly head. And it is shown in every action we are taking to protect the British people and protect people beyond Britain against the threat of terrorism."

Mr. Brown said he was angry and repulsed by the popular reception Megrahi received in Tripoli.  Megrahi maintains his innocence in the worst act of terrorism in British history.