By Clement Uwiringiyimana

KIGALI (Reuters) - Rwanda has launched an inquiry into the possible role of at least 20 French military and other officials in the 1994 genocide, the prosecutor general said on Wednesday, a move that will deepen already strained relations with Paris.

Rwanda has frequently had diplomatic rows with France since the genocide, when about 800,000 mostly ethnic minority Tutsis and moderates from the Hutu majority population were killed.

Rwandan officials have long accused France of supporting the former government of President Juvenal Habyarimana, a Hutu whose death when his plane was shot down in 1994 sparked the bloodbath.

Kigali temporarily broke diplomatic ties in 2006 with France when a French judge called for the trial of Rwanda's President Paul Kagame, a Tutsi whose rebels halted the genocide in 1994, over the death of Habyarimana. Kagame denies any role and has accused France of training soldiers who led the massacre.

Rwanda's prosecutor general Richard Muhumuza told Reuters he had been in contact with the French government in the past two or three weeks, but declined to name any of the French officials under investigation.

"Up to now, we cannot say that we already have something sufficient to make charges on those people," Muhumuza said.

"This is why we need to talk to them and hear their version of the story," he said, adding he hoped those named would agree to be questioned.

In a document dated Oct. 31, Rwanda's National Commission for the Fight against Genocide included top advisers to France's then-president, Francois Mitterrand, among the 22 French officials it accused of having a role in the genocide.

"DESPICABLE LIE"

French officials referred to remarks made on Nov. 16 by Defence Minister Jean-Yves Le Drian, when he criticized a possible Rwandan probe into French officers.

"To affirm that the French army took part in genocide is a despicable lie that I will not tolerate," the minister said then.

French Foreign Ministry spokesman Romain Nadal said Rwanda's request had been passed on to the Justice Ministry and that Paris was fully committed to bringing to justice the people that took part in the genocide.

"The seriousness of the crimes carried out in Rwanda means that justice must be handled impartially and calmly," he told reporters in a daily briefing.

The Rwandan commission said cases being pursued by the French judiciary into whether Kagame's rebel force had a role in bringing down Habyarimana's plane in April 1994 were motivated by a desire to mask the role French officials played.

"The refusal to end the judicial investigation (into downing the plane) and pronounce a dismissal against Rwandan leaders who ended the genocide is an attempt (at) concealing their responsibilities," the commission said.

Rwanda, a former German and Belgian colony, had strong ties with France until 1994. Under Kagame, the government has forged close links with the United States and Britain.

(Additional reporting by John Irish in Paris; Writing by Edmund Blair; Editing by Gareth Jones and Richard Lough)