Chadian rebels seized large parts of the capital Ndjamena Saturday, military and rebel sources said, leaving President Idriss Deby Itno holed up in the presidential palace.

The rebels have taken control of the outlying neighborhoods of the capital and a good part of the city centre after intense fighting with government forces, according to military sources.

By late afternoon Saturday, a relative calm had returned to Ndjamena, with only sporadic gunfire heard, but the situation remained tense around the president's residence.

"The forces of the president tried to push the rebels to the east of the city and take back some territory in the city centre," a military source in Ndjamena said.

Chadian rebel spokesman Abakar Tollimi said there were plans to attack the presidential residence on Saturday night.

"We suppose that Deby is inside. If he wants to leave we have no problem," Tollimi told AFP by satellite telephone earlier Saturday. "We control the situation, we control the city, there are some pockets of resistance."

Tollimi said government troops were surrounding the presidential palace and using heavy weapons against the rebels, who French military sources said numbered about 2,000 armed with machine-guns, assault rifles and rocket launchers.

According to witnesses, in certain neighbourhoods around people welcomed the rebels, who entered the city driving camouflage pick-ups and wearing olive-green battledress and white armbands.

International security organisations reported that looting had broken out.

Amid the confusing reports of the situation in Ndjamena, Deby insisted late Saturday that his forces were in control of the capital during a telephone call with Libyan leader Moamer Kadhafi, Libya's Jana news agency reported.

Kadhafi has been tasked by the African Union along with Congolese leader Denis Sassou Nguesso to find a negotiated solution to the crisis.

Chad's Foreign Minister Amad Allam-Mi told AFP that Deby was at the presidency and in control of the situation.

Allam-Mi accused Sudan of masterminding the rebel offensive with the aim to stop the so-called EUFOR Chad-Central African Republic mission that is to protect refugees from the war-torn Sudanese region of Darfur, just over Chad's eastern border, from deploying.

"Sudan does not want this force because it would open a window on the genocide in Darfur," he told Radio France Internationale, adding that Sudan was trying "to install a regime in Chad that will bow to it."

France sent an extra 150 troops to the central African country and prepared to evacuate its citizens, and the first group of 75 evacuees left Ndjamena late Saturday for Libreville, the capital of Gabon, from where they will fly on to France, French military officials said.

The wife and daughter of a Saudi employee at the Saudi embassy in Ndjamena were killed when a bomb hit the ambassador's residence, the Saudi foreign ministry announced.

The French foreign ministry strongly condemned "the attempt to seize power" in Chad by "armed groups from the outside."

French troops have been deployed in Chad since 1986. On Saturday they were reinforced with a combat unit of extra troops in response to the current situation, bringing to 1,450 the number permanently posted there.

French President Nicolas Sarkozy had two conversations with his Chadian counterpart to discuss the Chad crisis and medical situation, and held two emergency meetings, his office said.

French Foreign Minister Bernard Kouchner called for a truce and negotiations between Chad's government and the rebel forces, in a French television interview.

France has 1,500 citizens in Chad, a former French colony, with 85 percent of them in the capital.

"This is my second rebel attack," after an April 2006 bid, said a French businessman ready to leave the country, who has worked in Chad for two years and spoke on condition of anonymity.

"I don't want to come back to Chad. Everyday life is cumbersome. I'm totally pessimistic about the country's future."

Marina Kerguen, a mother of four, told AFP she would "come back when things have calmed down and school is open again. "I'ver never felt any sensitivity towards the French."

The United Nations also planned to evacuate its personnel in Chad to Cameroon, a spokesman said.

The United States said it was closely monitoring the fighting, as its embassy ordered the evacuation of staff families and selected employees.

The offensive -- the biggest since April 2006 -- comes after rebel leaders Timan Erdimi, Mahamat Nouri and Adbelwahid Aboud Makaye joined forces in mid-December after a peace pact with Deby fell apart.

African Union leaders meeting in Addis Ababa said the body "strongly condemns" the rebel attacks and "demands that an immediate end be put to these attacks and resulting bloodshed".