A Nato air strike in Tripoli has killed the son of Col Muammar Gaddafi, a Libyan government spokesman has said.
Saif al-Arab and three of Col Gaddafi's grandchildren died at a villa in the Bab al-Aziziya compound, he said.
The Libyan leader himself was there at the time but was unharmed, he added. Nato said it had hit a military target but denied targeting individuals.
Gaddafi supporters rallied outside Western diplomatic missions in Tripoli, reportedly causing some damage.
The UK Foreign Office said it was investigating reports that the residence of its ambassador had been "destroyed". The UK has withdrawn diplomats from Tripoli.
Saif al-Arab and three of Col Gaddafi's grandchildren died at a villa in the Bab al-Aziziya compound, he said.
The Libyan leader himself was there at the time but was unharmed, he added. Nato said it had hit a military target but denied targeting individuals.
Gaddafi supporters rallied outside Western diplomatic missions in Tripoli, reportedly causing some damage.
The UK Foreign Office said it was investigating reports that the residence of its ambassador had been "destroyed". The UK has withdrawn diplomats from Tripoli.