Coalition forces admits biggest mistake during four-month Libya campaign Reuters

Nato has admitted it was responsible for an air strike that killed civilians in Tripoli over the weekend.

"A military missile site was the intended target of air strikes in Tripoli last night," a statement said. "However, it appears that one weapon did not strike the intended target; there may have been a weapons system failure which may have caused a number of civilian casualties."

Earlier the Libyan government had said that a Nato missile had struck a house in a residential area of the Libyan capital, killing at least nine civilians, including two children.

The attack is the biggest mistake by coalition forces during the four-month campaign, at a time when Nato has been trying to increase the tempo of operations against the Libyan leader.

"Nato regrets the loss of innocent civilian lives and takes great care in conducting strikes against a regime determined to use violence against its own citizens," said Lieutenant-General Charles Bouchard, commander of Operation Unified Protector. "Although we are still determining the specifics of this event, indications are that a weapons system failure may have caused this incident," he added.

The Guardian understands that investigators are focusing on French aircraft that were flying over Tripoli to target a potential missile site. RAF planes were not thought involved. Nato was debriefing the pilots who flew sorties, as well as reviewing data from their aircraft. Before the admission of responsibility, a Nato official, speaking on condition of anonymity, had said there was confusion over the exact location of the explosion, and pointed out that the district in question was an anti-Gaddafi stronghold.

Reporters based in Tripoli were taken by government officials to the scene and then to a hospital, where they were shown the bodies of four people said to have been killed in the strike, including two infants.

Associated Press said journalists were escorted back to the site during the day, where children's toys, teacups and dust-covered mattresses could be seen amid the rubble. Foreign journalists in Tripoli are not allowed to travel and report freely and are almost always shadowed by government minders.

Libya's foreign minister Abdelati Obeidi said the Nato strike was a "pathetic attempt ... to break the spirit of the people of Tripoli and allow small numbers of terrorists to cause instability and disorder in the peaceful city".

Obeidi also called for a "global jihad" in response to the Nato action. "The deliberate bombing ... is a direct call for all free peoples of the world and for all Muslims to initiate a global jihad against the oppressive, criminal west and never to allow such criminal organisations as Nato to decide the future of other independent and sovereign nations," he said. However, Abdel Hafiz Ghoga, vice chairman of the rebel National Transitional Council, said in response: "We hold the Gaddafi regime responsible for having placed its military [installations] near civilian areas. So these losses [of civilians] are to be expected."

Gaddafi's forces used Grad rockets and mortars to bombard the rebel front lines in Dafniya, 15 miles west of Misrata. A medical official in Misrata hospital said that 10 rebels were killed and 54 wounded in clashes in Dafniya.