Sarkozy, in Chad to clarify the fate of the missing politicians and push for cross-party talks, met Deby at the palace where he was besieged during two days of heavy fighting on Feb 2-3 in which Deby said more than 400 civilians were killed.

A planned joint news conference was cancelled at the last moment and Sarkozy left without talking to journalists.

"Decisions have been taken, including the setting up of an international inquiry to shed light on all things that happened in N'Djamena during this period," Deby told reporters.

France, Chad's former colonial ruler and long-term ally, came to Deby's aid during the attack, delivering ammunition to his troops and drafting a U.N. resolution in his support.

That prompted Deby to consider pardoning six French aid workers in jail in France for trying to kidnap 103 Chadian children in a high-profile case that tested diplomatic ties.

But since the rebels withdrew, France has steadily increased pressure on Deby's administration to talk to the opposition and produce three politicians dragged from their homes during the fighting, which aid workers say killed more than 250 people.

Former President Lol Mahamat Choua has been released under house arrest, but Ibni Oumar Mahamat Saleh and Ngarlejy Yorongar have yet to be found -- although Deby's government says Yorongar was spotted last week in N'Djamena.

Before leaving for Chad, Sarkozy met representatives from six international non-governmental organisations, including Human Rights Watch, which has said he should not visit Chad until the government proved the opposition members were alive.

"UP TO YOU TO MAKE PEACE"

Sarkozy's spokesman said earlier Sarkozy wanted a credible inquiry into the politicians' disappearances and a resumption of political dialogue, and would tell Deby friendship between the two states could grow only if democracy in Chad accelerated.

"It is up to you to make peace. We can help you but we can't achieve reconciliation for you," Sarkozy told members of Deby's ruling party who sit on a committee overseeing political reforms agreed with the opposition parties in August.

Carla Bruni-Sarkozy, the model-turned-singer making her first overseas trip as first lady after marrying the French president this month, met the wife of missing opposition coalition leader Saleh at the French embassy in N'Djamena.

Saleh's anti-Deby coalition stepped up pressure on France on Tuesday, accusing it of overstepping the terms of a military pact with Chad and of backing Deby "whatever he has done".

Chadian authorities say they detained Choua, 70, as a "prisoner of war" on February 3 and that he will remain under house arrest while the inquiry against him continues. They say they are not holding the two other opposition figures.

European Union aid commissioner Louis Michel and French Foreign Minister Bernard Kouchner, both among a large delegation accompanying Sarkozy to Chad and South Africa, met Choua.

"The way he was taken from his home was quite brutal. He was scared and thought he was going to be executed," Choua's spokesman Mahamat Allhou Tahir told Reuters.

The European Union is deploying a 3,700-strong force in Chad to protect several hundred thousand Sudanese and Chadian refugees living in camps in the dangerous east of the country.

But critics have demanded more action to restore peace.