NATO has admitted another accidental airstrike by its forces may have killed civilians in the Libyan capital, Tripoli.

The alliance said the air strikes were launched against a military missile site in Tripoli Sunday, but “one weapon did not strike the intended target” because of a possible “weapons system failure.” NATO said it regretted the “loss of innocent civilian lives.”

Libyan officials said Sunday, NATO warplanes struck a residential neighborhood and killed nine people. Two children were among the dead.

This was the second recent admission of deadly error by coalition forces. On Saturday, NATO acknowledged that aircraft under its command had accidentally hit a rebel column near the oil refinery town of Brega on the frontline between the rebel-held east and the mainly government-held west on Thursday. The number of casualties in that attack were not revealed.

Elsewhere Sunday, rebels and medical officials in Libya say fighting near the rebel-held western city of Misrata has killed at least nine people and wounded more than 50 others.

The officials said forces loyal to Libyan leader Moammar Gadhafi used heavy artillery to pummel Dafniya, just west of Misrata.

On Saturday, the coalition called Libyan government claims that alliance airstrikes are targeting civilians “outrageous.” Spokeswoman Oana Lungescu said it is Libyan leader Moammar Gadhafi and his forces who have been “systematically and brutally attacking” the Libyan people.