Police and diplomats in Mali say a car bomb killed four people including United Nations peacekeepers Wednesday in the northern town of Aguelhoc.
The victims are said to be peacekeepers from Chad and possibly soldiers from Mali.
No one has claimed responsibility.
Chad's U.N. mission, known as MINUSMA, said a car packed with explosives was driven up to the entrance of the camp, which also houses Malian soldiers, and detonated there. The head of MINUSMA Albert Koenders called the attack
"cowardly and odious".
Mali has been in chaos since 2012 when Tuareg rebels and later al-Qaida-linked militants took advantage of a military coup in the capital to seize control of the north.
French-led forces pushed the Islamists out, but violence continues as the U.N. and Mali's neighbors struggle to salvage a faltering peace process.
The French intervention allowed the Tuaregs to retain control of parts of their stronghold of Kidal, southeast of Aguelhoc, pending peace talks after they pledged to break ties with their Islamist allies.
But negotiations have largely stalled and observers say the lines between the northern separtists and Islamist groups remain blurred.
Some information for this report was provided by AP and Reuters.