Reports suggest that this could be the deadliest battle since US-led forces toppled the Taliban regime in Afghanistan in October 2001.
Though the number of dead is yet to be confirmed, NATO said the figure was arrived from information received from Afghan officials and local residenty. Four Canadian soldiers died in the operation.
The Afghan-NATO alliance denied civilian casualties but an Afghan government spokesman said a number of civilians died in the operation.
On Saturday, a British aircraft supporting the operation crashed due to a technical snag, killing 14 British soldiers.
NATO forces took control of the security in southern Afghanistan from the US-led coalition in August. More than 1,800 people, mostly Taliban, have died in the last four months.
One hundred and thirty foreign troops have died in Afghanistan this year.
