In a letter to the United Nations Security Council, Libya said it "accepts responsibility for the actions of its officials" in the midair destruction of Pan Am Flight 103 on 21 December 1988, above Lockerbie, Scotland.
In the letter, Libya renounced “terrorism”, pledged cooperation in criminal investigations and said it would pay compensation expected to total $2.7 billion for the 259 people on the plane and the 11 on the ground who died.
If the payments are made, the US and Britain had made clear they would enable lifting of the United Nations sanctions imposed on Libya in 1992 over the bombing.
But on Friday, in a harshly worded statement, White House spokesman Scott McClellan said restrictive US sanctions would stay in place.
"The United States will intensify its efforts to end threatening elements of Libya's behaviour, and US bilateral sanctions on Libya will remain in full force until Libya addresses these concerns."
--US spokesman Scott McClellan
Washington had concerns about Libya's suspected pursuit of weapons of mass destruction, its "destructive role" in regional conflicts in Africa and its "poor human rights record and lack of democratic institutions”, he said.
"The United States will intensify its efforts to end threatening elements of Libya's behaviour, and US bilateral sanctions on Libya will remain in full force until Libya addresses these concerns," McClellan said.
The end to UN sanctions has no practical implication because those sanctions were suspended in 1999 after Libya turned over two Libyan suspects Abdel Basset al-Megrahi and Al-Amin Khalifa Fahima for trial.
Megrahi, a Libyan intelligence agent, was convicted of the crime in 2001 while Fahima was acquitted.
Earlier, Libya accused France of blackmail after Paris threatened to block a deal lifting UN sanctions in exchange for compensation for the 1988 Lockerbie bombing France is demanding a matching payout for the bombing of a French airliner.
"France is using pressure and blackmail and we do not accept this," said Libyan Foreign Minister Abdel Rahman Shalgham on Friday.
France, which has a veto on the UN Security Council, has made clear it wants similar compensation for the families of 170 people killed when a plane operated by French airline UTA was blown up the following year.
"We have reached a comprehensive, global agreement with the Americans, the British and the lawyer for the families to resolve this problem," Shalgam said.
"From now on it's between the French and the Americans. If the French want to use their veto, it's their decision."
The UTA plane was carrying 54 French nationals and 116 others on a flight from the Democratic Republic of Congo to Paris when it blew up over Niger on September 19, 1989.
Ten months later a Congo-Brazzaville national came forward to declare a Libyan diplomat had given him an explosives-packed suitcase and instructed him to hand it to a passenger boarding the plane.
Another Libyan, Abdel Basset Ali al-Megrahi, was sentenced to life in prison by a Scottish court in January 2001 for carrying out the Lockerbie bombing, while a second Libyan was acquitted.