According to the news, for what did NATO apologise?

The commander of the Libyan rebel forces, Abdul Fatah Younis, says NATO has apologised for mistakenly attacking a column of rebel tanks near Ajdabiya, in the east of the country. General Younis said the air strike, which killed several rebels, had occurred despite NATO being warned that the tanks were being moved to the frontline. Wyre Davies is in Benghazi.
    The rebel commanders were insisting that NATO planes fired upon them, and there’s been a line out of the political rebel leadership tonight in Benghazi saying this was actually the work of the remnants of Gaddafi’s air force. While that isn’t impossible, I think it’s highly improbable. Part of the problem today may have been that the rebel forces sent in for the first time in a long time a lot of very heavy armour. Tanks and rocket launchers were sent in on the ground. And whether those were mistaken for Gaddafi armaments, we don’t know, but that could be one explanation.
    Elsewhere in Libya, a relief ship carrying emergency supplies of food and medicine has arrived in the western city of Misrata, which is being besieged by government forces. It’s delivering hundreds of tons of high-energy biscuits, flour and water purification tablets, as well as enough medicine to last 30,000 people for a month. The ship was chartered by the UN World Food Programme.