TRIPOLI, Libya – NATO said Saturday it mistakenly struck a column of Libyan rebel vehicles in an airstrike near an eastern oil town two days earlier. The alliance expressed regret for any casualties that might have resulted.

NATO has accidentally hit rebel forces before in its air campaign to protect civilians in the civil war between Moammar Gadhafi’s military and the fighters trying to end his more than four decades in power.

The rebels have also complained that NATO’s strikes have not helped them gain decisive momentum against the Libyan leader’s better trained and equipped military, which still has firm control over most of western Libya. The rebels control much of the east.

A doctor in the city of Ajdabiya said the bodies of four rebel fighters were brought to his hospital about the time of Thursday’s strike, but it was not possible to confirm whether they were killed in the bombardment.

Earlier Saturday, NATO accused Gadhafi’s forces of using mosques and children’s parks as shields for his military operations and said the Libyan leader is “brutally attacking” his people.