The alliance said the intended target was a missile site, but "it appears that one weapon" did not hit it.

The Libyan government earlier said Nato had bombed a residential area, killing nine civilians, including two babies.

Meanwhile, rebel leaders said their administration had run out of money as donors' pledges had not materialised.

They told a news conference in the eastern city of Benghazi that they were still waiting for funds that should have been deposited by last week.

Nato is enforcing a UN resolution to protect civilians in Libya. But on June 19 evening, the commander of operation Unified Protector, Lt Gen Charles Bouchard, said: "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.”

The statement said that more than 11,500 sorties had already been conducted and "every mission is planned and executed with tremendous care to avoid civilian casualties".

Nine people were killed in June 19 attack, including two babies, and another 18 people injured.

Libyan Deputy Foreign Minister Khaled Kaim said the incident represented a "deliberate targeting of civilian houses".