Militants killed five people including a French citizen and a Belgian citizen in a gun attack on a restaurant in the capital of Mali, authorities said on Saturday.

Mali's desert north, where French forces wrested control of territory from separatist rebels and al Qaeda-linked militants, is hit by frequent political violence, but this is the first such attack for years in the capital Bamako in the south.

Two Malians died in the overnight attack on the La Terrasse, a restaurant frequented by expatriates, a senior Malian intelligence official told Reuters, while the nationality of the fifth dead person was unclear.

There were few details about the attack and the attackers, but the official said two people had been arrested.

"The zone where the shooting took place is under the control of the security forces. Two Europeans and two Malians have been killed. The security forces are conducting an operation to ensure there are no other surprises," the source said.

French Foreign Minister Laurent Fabius confirmed a French citizen was among those killed. He condemned the attack and said it strengthened France's resolve to "fight terrorism in all its forms".

French forces wrested control of northern Mali two years ago but insurgents continue to mount attacks. France has more than 3,000 soldiers in West Africa as part of a counter-insurgency force against al Qaeda-linked militants.

The French embassy in Mali said on Saturday it had alerted its citizens and beefed up security.

Belgian Foreign Minister Didier Reynders also condemned the violence and said it may have been a terrorist attack. He was speaking to reporters during a conference of foreign ministers in Riga.

Mali's government signed a preliminary peace proposal on Sunday meant to end fighting with northern separatists, but the Tuareg-led rebels demanded more time before agreeing to any accord.