Libyan rebels say five of their men were killed when NATO mistakenly bombed them on the road between Brega and Ajdabiya.
NATO has admitted firing on the road, but a spokesman said that forces loyal to Gaddafi were also on the same road.
Speaking at Joint Forces Command in Naples, Rear Admiral Russell Harding said:
“It is, and was, a very fluid situation on the road between Brega and Ajdabiya. In other words there were vehicles going backwards and forwards. But the key point was, those units that we had previously seen in Misrata and other areas attacking civilians, were on that road”.
He also said until the incident on Thursday, NATO had not known that the rebels had started to use tanks in the area.
There was no apology from NATO, but rebel leaders said that while they wanted an explanation, it is not likely to cause tension between them.
It is the second time in a week that the insurgents have blamed NATO for bombing them by mistake.
Thirteen were killed in an airstrike not far from the same spot last Saturday.