The controversy was discussed on Friday by members of the Security Council, which is divided on the sanctions.
The Dutch ambassador who heads the UN sanctions committee, Peter van Walsum, criticised France for rejecting his request to delay the flight. And the United States accused France of breaking sanctions.
About 60 French doctors, artists and sports personalities were on board the plane, which landed in Baghdad at 1520 local time (1120 GMT) on Friday to provide medical assistance and take part in a cultural festival.
France argued that as the flight was not commercial, it needed only to notify the UN, and did not need special permission.
But the US described it as a "blatant violation" of the sanctions.
"The flight was done in clear defiance of the UN and its established procedures," State Department spokesman Richard Boucher said.
France, however, maintains that it is not trying to erode sanctions, but merely interpreting UN resolutions in a more liberal way than Washington and London.
"You will not be surprised we don't have the same analysis of the situation," the French ambassador, Jean-David Levitte said.
Security Council divided
"For many years now we have considered there is no flight embargo against Iraq."
The flight was arranged by a private French group opposed to the international sanctions imposed after Iraq's invasion of Kuwait in 1990.
The controversy was discussed on Friday by members of the Security Council, which is divided on the sanctions.
British Ambassador Jeremy Greenstock said the issue would also be raised in the European Union, which bans flights to Iraq.
"It is the only instance I can remember of a flight being notified to the committee but then going against the procedures of the committee to wait 24 hours," he said.
Further flights
Mr van Walsum said he had was aware there were differing interpretations of the UN sanctions. He added he had asked for the flight to be delayed so he could ask each of the 15 members of the sanctions committee if they objected to the flight.
Last week Russia flew a passenger flight to Iraq carrying humanitarian aid and a number of oil executives.
But it gave the UN sanctions committee a few days' notice, enabling other countries to decide whether they wanted to raise any objections. None, however, did.
France, for its part, gave the committee only a few hours' notice.
A second French group has announced plans for another flight on 29 September.
Iraq reopened its international airport last month to enable it to receive international flights again, despite the sanctions.
Both France and Russia, close trading partners of Iraq before the invasion of Kuwait, want the sanctions eased or lifted.
All security members say they want to see Iraqi President Saddam Hussain accept the return of UN weapons monitors to Iraq.
But the BBC's UN correspondent, Mark Devenport, says that with prominent countries at loggerheads over sanctions, the Iraqi leader is unlikely to feel under any immediate pressure to give in to the council's demands on weapons inspections.