* In trucks and on foot, M23 rebel fighters pull out
* UN: 750 have left, rest expected out by end of Saturday
* Pullout provides breathing space for possible negotiations
Hundreds of rebel fighters, singing and brandishing weapons, pulled out of Congo's eastern border city of Goma on Saturday, raising hopes for negotiations to end the insurgency.
The withdrawal of the M23 rebel movement from Goma on Lake Kivu, a strategic hub in Democratic Republic of Congo's war-scarred east, was agreed in a deal brokered by presidents of the Great Lakes states under Uganda's leadership a week ago.
Kieran Dwyer, spokesman for the U.N. Department of Peacekeeping Operations in New York, said the U.N. peacekeeping mission in Congo, or MONUSCO, confirmed the pullout was completed.
"The M23 has today withdrawn from Goma city in eastern DR Congo," he said in a statement. "MONUSCO mobilized 17 rapid reaction units in the city throughout the day to monitor the M23 withdrawal which took place in a largely orderly manner."
"MONUSCO troops secured key installations including the Central Bank, Governor's House and communications infrastructure at Goma Hill," Dwyer said.
Goma's fall on Nov. 20 to the Tutsi-led M23 insurgent group, which routed U.N.-backed government forces, triggered a diplomatic scramble to prevent a wider escalation of the eight-month-old rebellion in the conflict-prone region.
The rebels had said they would fight to topple Congo's president, Joseph Kabila, and march on the capital, Kinshasa, 1,600 km (1,000 miles) to the west. U.N. experts accuse Rwanda and Uganda of supporting the revolt, a charge both strongly deny.
In the centre of Goma, blue-helmeted U.N. peacekeepers from Uruguay in white armoured vehicles watched as camouflage-clad M23 fighters scrambled on to the back of flatbed trucks with battered suitcases and other belongings before driving off.
RESIDENTS LINE STREETS
Residents lined the streets leading out of the city to watch as the truckloads of singing rebels drove out, heading for previously agreed positions 20 km (13 miles) north of Goma from which M23 launched its lightning offensive two weeks ago.
On the dusty road by the U.N.-controlled airport, about 100 rebels trudged out of town on foot. Some of the trucks leaving Goma carried crates of captured munitions and military supplies.
M23 military chief Sultani Makenga, who is under a U.N.-imposed assets freeze and travel ban for leading the revolt, told reporters the rebel withdrawal was in response to a request from Ugandan President Yoweri Museveni.
"We are leaving for peace," Makenga said, following a brief ceremony in which a squad of around 40 M23 fighters, wearing mottled green camouflage uniforms, peaked caps and black gumboots, first paraded and then sang and danced.
MONUSCO's Sellassie said she expected the Congolese army to return to Goma within 36 hours. Congolese police officers brought in to help keep order were already on the streets.
If there are no hitches, a full rebel withdrawal from lakeside Goma, which lies in sight of the towering Mount Nyiragongo volcano, will provide breathing space for possible follow-up negotiations between the rebels and Kabila.
Humanitarian agencies say hundreds of people have been wounded and thousands displaced by the recent fighting.
Goma lies at the heart of Congo's eastern borderlands, which have suffered nearly two decades of conflict stoked by long-standing ethnic and political enmities and fighting over the region's rich resources of gold, tin, tungsten and coltan. The latter is a precious metal used to make mobile phones.
WAY OPEN FOR TALKS?
The Congolese president has said he is willing to listen to the rebels' grievances, but there is considerable mistrust between the two sides and Kabila faces pressure from within his own army to pursue a military solution rather than talks.
"If Kabila provokes us, we will come back," M23's Makenga said. "If he wants peace, there will be peace, if he wants war, there will be war," he added.
Uganda's junior foreign minister, Asuman Kiyingi, told Reuters that Kampala would encourage the two sides to talk. "Now that M23 has withdrawn, it's important that the Kinshasa government also addresses the grievances of these people (M23)," he said.
Asked about prospects for talks, Congo government spokesman Lambert Mende said, "It's the president who has the intuitive and only him, it's for him to decide how things proceed."
Some Goma residents jeered as the trucks carrying departing rebels lurched through the dusty streets, but no major incidents or disturbances were reported.
On Friday, the pullback plan appeared to run into problems, including a dispute over abandoned army supplies the insurgents wanted to take with them.
In the face of evidence supplied by U.N. experts about Rwandan involvement in the rebellion, a number of Western donors have frozen aid to Kigali. Rwandan President Paul Kagame has angrily rejected the charges against his government.
In the latest move, Britain, Rwanda's largest bilateral donor, said on Friday it was withholding 21 million pounds ($34 million) of budget support.
Rwanda has twice invaded its western neighbour Congo over the past two decades, at one point igniting a conflict dubbed "Africa's World War" that drew in several countries.
It has justified its interventions by arguing it was forced to act against hostile Rwandan Hutu fighters who had fled to Congo after the 1994 Rwandan genocide that saw 800,000 Tutsis and moderate Hutus killed by Hutu soldiers and militia.
The M23 rebels said they took up arms over what they call the government's failure to respect a March 23, 2009, peace deal that envisaged their integration into the Congolese army.
They have since broadened the scope of their movement, which takes it name from the peace deal date, declaring their aim to "liberate" the entire Central African nation and oust Kabila.
Aid agencies say more than 5 million people have died from conflict, hunger or disease in Congo since 1998.