Foreign Secretary William Hague said on Sunday he was expelling the Libyan ambassador following attacks on the British embassy in Tripoli blamed on Moamer Kadhafi's forces.
Hague confirmed reports that the British diplomatic compound in the Libyan capital had been destroyed, and said there had also been attacks on other countries' diplomatic missions in Tripoli.
"As a result, I have taken the decision to expel the Libyan ambassador. He is persona non grata pursuant to article nine of the Vienna Convention on Diplomatic Relations and has 24 hours to leave the country," he said.
Earlier, the Foreign Office said it had reports that the British diplomatic compound in Tripoli, which includes the ambassador's residence and staff offices, had been "destroyed".
The embassy attacks came just hours after the Libyan regime accused NATO of killing Kadhafi's youngest son and three grandchildren in raids on Saturday evening.
The British ambassador was recalled from Libya at the start of the conflict and London currently has no diplomatic staff in Tripoli, although a Foreign Office team is based in the rebel-held city of Benghazi.
"I condemn the attacks on the British embassy premises in Tripoli as well as the diplomatic missions of other countries," Hague said in a statement.
"The Vienna Convention requires the Kadhafi regime to protect diplomatic missions in Tripoli. By failing to do so that regime has once again breached its international responsibilities and obligations.
"I take the failure to protect such premises very seriously indeed."
However, Hague stressed that the attacks "will not weaken our resolve to protect the civilian population in Libya".
Britain has been at the forefront of a bombing campaign in Libya to enforce a UN resolution authorising the use of force to protect civilians from fierce fighting between Kadhafi's forces and opponents of his four-decade rule.