By Francois Murphy

PARIS (Reuters) - Six French police officers were attacked at an airport in Guinea last week while taking two illegal immigrants back to their country of origin, a police report obtained by Reuters said.

The incident could reignite a French debate over the controversial policy of "escorting" illegal immigrants on commercial flights in which police sometimes use force on those resisting repatriation.

"Suddenly and violently we were attacked," the police report said, describing the scene as the French police tried to hand over the two men to the authorities at Conakry airport while passengers and other people nearby shouted insults at them.

"We received a multitude of punches and kicks from the two expelled, some passengers but also from two police we later recognised at the police station," said the report, which also described last Thursday's encounter as an "ambush".

The French police were not available for comment.

An official at Guinea's airport police, who asked not to be identified, said judicial police were investigating the case.

"One of the passengers claims he was mistreated during the whole flight," he said.

"We have never had a similar case before because normally when there is resistance the airline refuses to fly."

Many of France's immigrants come from Africa, where it once held several colonies. The clash highlights the hostility some Africans harbour towards French immigration policy.

"All this happened in front of one of their (Guinean) officers," said Paul Le Guennic, national secretary of police union UNSA, confirming the incident.

The French policemen suffered injuries ranging from a cut lip and chin to rib and back injuries, the report said. They also faced verbal insults at the airport police station.

"A policeman in uniform insulted us in these terms: 'Dirty dog, son of a whore, I'm going to kill you'," the report said.

A female police officer later told them: "You savages. Colonisation is over." Guinea is a former French colony.

The report said that when the police boarded their first flight with the men in Paris, the pair had to be held in place while they shouted, spat, and tried to bite the police.

Some passengers protested against the way the men were being treated and one told the police officers some passengers had called Conakry to arrange for a "hostile welcoming committee".

A French foreign ministry spokesman said Guinean authorities pledged to take steps to avoid a repeat of the incident.