* Thousands of Muslims seek to escape from country's south
* Attack was second public lynching this week
* ICC to open preliminary investigation of alleged crimes (Adds background on ICC investigation, quote from medical charity, PM comment)
By Media Coulibaly and Thomas Escritt
BANGUI/AMSTERDAM, Feb 7 (Reuters) - An angry crowd killed and mutilated a man who fell from a truck filled with Muslims fleeing the capital of Central African Republic on Friday, witnesses said, while an international court said it would investigate alleged crimes committed there.
The attack was the second daylight lynching reported this week as violence rages between the majority Christian population and Muslims accused of links to Seleka, a former rebel grouping that seized power last year and ruled until January.
Members of the crowd killed the man and cut off his hands and genitals, Peter Bouckaert, emergencies coordinator at campaign group Human Rights Watch, told Reuters.
"It was easily over 10,000 people and that's an extremely conservative estimate," he said, referring to the convoy's size.
The Red Cross was called to collect the mutilated body, and found three other corpses on Friday, said the organisation's director in the country, Pastor Antoine Mbao Bogo.
In The Hague, the International Criminal Court said on Friday it would open a preliminary examination into crimes, including killings, acts of rape and sexual slavery allegedly committed during the conflict.
"The plight of civilians in CAR since September 2012 has gone from bad to worse," the court said. Some victims appeared to have been singled out on religious grounds, it added.
A Reuters witness saw around 20 pick-up trucks leaving Bangui early on Friday morning in the latest stage of an exodus of Muslims from the capital and other parts of the south.
MUSLIMS MOVE OUT
African peacekeepers from Chad protected the convoy and fired teargas to disperse crowds who sought to mob two trucks left behind.
More than a quarter of the population of the former French colony has fled their homes as part of the upheaval.
"Entire neighbourhoods are being emptied of Muslims. Their presence is being erased from this city," said Bouckaert.
"Their mosques are being demolished brick by brick," he said, adding he had seen only one mosque remained out of eight in one neighbourhood of Bangui.
Medical charity MSF said on Friday that attacks on Muslims were increasing, estimating that 40,000 people had already fled to neighbouring Chad and Cameroon.
"We are currently witnessing direct attacks against the Muslim minority. We are concerned about the fate of these communities trapped in their villages, surrounded by anti-balaka (Christian militia) groups...," said Martine Flokstra, MSF emergency coordinator.
The Muslims are under threat because they are identified with Muslim Seleka fighters, who seized power last March and embarked on a 10-month occupation of towns and cities marked by looting, torture and murder.
Resentment against the Seleka among the country's Christian majority led to the formation of Christian "anti-balaka" militias, meaning "anti-machete" in the Sango language, further fanning the flames of inter-religious bloodshed.
The presence of 1,600 French soldiers and 5,000 African troops has failed to stop the violence, which the United Nations says has killed more than 2,000 people.
Catherine Samba-Panza, Bangui's mayor, was named interim president last month, replacing former interim President and Seleka head Michel Djotodia who stepped down under international pressure for failing to stop the violence.
The difficulties she faces in restoring control were emphasized on Wednesday when soldiers lynched and mutilated a suspected rebel at a military ceremony she had attended in the capital.
Interim prime minister Andre Nzapayeke condemned the "barbaric" act on Friday and pledged to track down those responsible.
Rebels who have fled Bangui in recent weeks are regrouping in the country's northwest where they have launched renewed attacks against civilians, according to Human Rights Watch.
The rights group also accused Chadian peacekeepers of facilitating the movements of Seleka leaders responsible for a new wave of atrocities. Bouckaert said Seleka leaders were among the Muslims who left in the convoy.
Mineral-rich Central African Republic has a history of political instability and has seen five coups and several rebellions since winning independence from the French in 1960.
But inter-religious violence had been rare and many blame a political battle for control over resources in one of Africa's weakest states, split along ethnic fault lines and worsened by foreign meddling. (Writing by Emma Farge and Matthew Mpoke Bigg; Additional reporting by Emmanuel Braun; Editing by Tom Heneghan and Andrew Heavens)