By Richard Valdmanis
SEGOU, Mali, Jan 23 (Reuters) - Mali's army sealed off the central town of Sevare to journalists on Wednesday following allegations by residents and human rights groups that government soldiers had executed Tuaregs and Arabs accused of collaborating with Islamist rebels.
The allegations, which have been denied by the Malian army, threatened to cast a shadow over a French-led operation to drive Islamist fighters allied to al Qaeda from northern Mali.
They also pointed to a risk the internationally backed military campaign could trigger further racially motivated killings in Mali's desert north, home to complex mix of ethnic groups.
A Reuters reporter saw at least six bodies in two areas of the Walirdi district of Sevare. Three of them were lying, partly covered in sand, near a bus station and showed signs of having been burned. Three more had been thrown into a nearby well.
Oumar, a jewellery salesman who has long worked closely with Sevare's Tuareg community, said his friend Hamid Ag Mohamed had been arrested by soldiers shortly after President Diouncounda Traore declared a state of emergency on Jan. 11, handing the military sweeping powers.
"I tried to call him but the phone rang and he never answered. The next day his body was behind the station in Sevare," said Oumar, who declined to give his family name for fear of reprisals.
"There were many other bodies there and in wells. It was only Tuaregs and Arabs, some with beards."
The International Federation for Human Rights (FIDH), a global network of rights groups based in Paris, said it had evidence Mali's army had executed at least 11 people in Sevare from Jan. 10 onwards. It called for an independent enquiry.
It also reported that two Tuaregs were killed in the Niono region, further to the west, and it cited other unconfirmed reports of summary executions in western and central Mali.
"AN EXPLOSIVE COCKTAIL"
FIDH said victims were people accused of collaborating with the jihadists or of possessing weapons, those without the proper identification documents or simply people who resembled members of lighter-skinned Arab and Tuareg ethnic groups associated with the rebels.
The army is dominated by black Africans from southern Mali.
"These reprisals, linked with the extreme tension which already exists between communities, is an explosive cocktail which makes one fear for the worst, especially in the context of the reconquest of the north," said Souhayr Belhassen, president of FIDH.
Many in Mali's powerful military, which toppled the government in March last year, are furious at the Tuaregs for precipitating a crisis which has displaced some 400,000 Malians and threatened to split the landlocked state in two.
The MNLA Tuareg separatist group seized control of northern Mali in April last year in a power vacuum left by a military coup.
The MNLA, however, were quickly pushed aside by an Islamist alliance grouping al Qaeda's north African wing AQIM and Malian militant groups Ansar Dine and MUJWA.
Ethnic tensions have been fuelled by abuses on both sides. Dozens of Malian soldiers were slaughtered by rebels in the remote northern town of Aguelhoc in January 2012 when they ran out of supplies and ammunition.
The International Criminal Court said on Jan. 16 it was opening an enquiry into war crimes in Mali.
While some Tuaregs support the Islamists, particularly in the Ansar Dine faction founded by former separatist leader Iyad ag Ghali, many of them do not and resent its fundamentalist form of Islam at odds with the region's traditional moderate Sufi beliefs.
French Defence Minister Jean-Yves Le Drian acknowledged on Wednesday, in an interview with France 24 television, that "there are risks" that violent reprisals had been carried out.
"We have to be extremely vigilant and the president (Francois Hollande) is counting on the sense of responsibility of the Malian army's officers to avoid any violence," he said.
Malian Lt. Diaran Kone confirmed that Sevare had been closed to journalists but could not give a detailed reason. "It has to do with the situation on the ground," he said.
Sevare is more than 100 km away from the latest reports of fighting where French jets are pounding rebel bases in the far north.
Fearing attacks on Tuaregs by the army should they retake northern cities such as Kidal and Timbuktu, the MNLA has offered to help the international mission fight the Islamists, something Bamako is unlikely to countenance.
David Gressly, U.N. Regional Humanitarian Coordinator for the Sahel, said he had no firm evidence of ethnic reprisals.
"We have heard of rumours of abuses which we cannot confirm and we are asking for more access to see what is happening on the ground," Gressly said.
The United Nations is sending a team to Sevare to investigate the claims and has requested Malian authorities to strongly denounce such activities.
Malian Prime Minister Django Cissoko, placed in power by the army in December after it briefly arrested his predecessor, said in a statement late on Wednesday he had instructed the armed forces to strictly respect human rights. (Additional reporting by Bate Felix in Bamako and John Irish in Paris; Writing by Daniel Flynn; Editing by Jon Hemming)