Some diplomats accused France of trying to stall an operation the alliance hopes to launch in Iraq next month with an advance party of some 20 to 30 personnel.
Others said France was by no means isolated. They argued that Washington was holding things up by demanding that the mission be commonly funded - rather than paid for by nations providing training - and that it should come under the command of both NATO in addition to the US-led occupation force in Iraq.
"It's not over, there will be another meeting tomorrow morning," an official said as ambassadors of the 26 NATO nations emerged empty-handed from their second meeting of the day on Iraq.
"There is a debate and there is no consensus yet."
Meanwhile, the US was attempting to persuade Arab allies to contribute troops to Iraq.
On Wednesday, US Secretary of State Colin Powell discussed the possibility of deploying troops from Arab or Muslim nations in Iraq with his Saudi Arabian counterpart Foreign Minister Saud al-Faisal on Wednesday.
"We had a preliminary discussion with the secretary on that," the foreign minister told reporters at a joint news conference.
He gave no details which countries might contribute and what conditions may be attached.
A deployment by Muslim nations would help the US save face after US-led occupying forces in Iraq were reduced by the withdrawal of the Philippines, Spain, the Dominican Republic, Nicaragua and Honduras.
Last week, Egypt ruled out sending troops and Iraq has previously said it would not accept troops from bordering countries.