PARIS (AP) — Malian authorities are investigating claims of torture, killings and reprisals by its own soldiers against minority civilians with alleged links to Islamist militants — accusations that threaten to jeopardize international support for fighting terrorism in the Sahara.

Malian Foreign Minister Tieman Coulibaly insisted to The Associated Press that his government is taking the claims seriously and won't tolerate such "atrocities." But he acknowledges that it's a tough and sensitive task to investigate them in a poor, violence-scarred country with a weak, military-led government.

Concerns have mounted in recent weeks about abuses by Malian forces amid the French-led military campaign against al-Qaida-linked rebels who overran northern Mali last year. Arab and Tuareg families are particularly afraid of reprisals, minorities who are accused of having aided the rebels.

The AP has documented a shallow grave where the bodies of two Arabs from Timbuktu were dumped — two men last seen alive being arrested by Malian forces. One of the last Arab residents of Timbuktu was picked up by Malian troops last week, the elderly man's hands bound and body trembling. The reason for his arrest and his whereabouts are unclear.

"The government will not tolerate atrocities. The government will not accept discrimination," Coulibaly said Tuesday in Paris.

He insisted the goal is to arrest suspected terrorists, not torture or kill them, and said that the lighter-skinned minorities in the north are not being unfairly targeted.

"We can't, in the name of avoiding discrimination, let an Arab or Tuareg go just because he's Arab or Tuareg, if he is guilty," he said.

He said four or five specific accusations are currently under investigation by Malian military authorities.

Asked whether they're capable of conducting full, transparent and fair investigations, he acknowledged, "It's hard." He said Mali has asked for U.N. observers to come and monitor Malian forces to prevent abuses.

Mali is hoping for U.S. and European aid for development and help for the Malian military. But Mali has an unstable government installed by the army after a coup last year, and international partners question whether it will be ready to run the country if French forces start pulling out next month, as they have pledged.

Ethnic tensions between southern Malians and the Tuaregs and Arabs remain high. And securing the north is proving harder as the month-old French-led operation drags on.

French and Malian forces quickly took back northern cities such as Timbuktu, but for weeks have been unable to retake the city of Kidal farther north. "The city is not secured," Coulibaly said Tuesday.

And extremists are mixing in with local populations in cities where French and Malian forces have moved in, making them harder to find.

"In fleeing they left behind ... indoctrinated youth, drugged, who are ready to go and blow themselves up anywhere. That's harder to fight than a conventional army," Coulibaly said.

Mali was plunged into turmoil after a coup in March 2012 created a security vacuum that allowed secular rebel Tuaregs to take half the north as a new homeland. In the following months, the rebels were kicked out by the Islamic extremists who imposed strict Shariah law.

France, fearing that its former colony was becoming a haven for international terrorists, launched a military operation on Jan. 11 in Mali after the extremists started to move south toward the capital.