Soldiers attending to wounded and casualties in the aftermath of the suicide bomb attackAFP The attack targeted soldiers and members of rival armed groups who conduct regular patrols in a bid to secure northern Mali

At least 50 people have been killed in northern Mali in a car bomb attack on a military base, officials say.

A vehicle packed with explosives detonated at a camp housing soldiers and members of rival armed groups in the region’s main city, Gao.

Mali’s northern desert region has been restive since it was captured by militant Islamists in late 2012.

Despite French military intervention in 2013, the region remains tense with sporadic attacks and kidnappings.

A source at the UN Mission in Mali (Minusma) is quoted by the AFP news agency as saying it was a suicide attack.

The victims were involved in conducting patrols in this highly volatile area under a deal backed by the UN in a bid to stop the violence there.

Gao in northern Mali was at the cradle of rebel uprisings and a sanctuary for Islamist fighters.

It is not the first time the military in Mali has been targeted by a deadly attack.

In July last year, about 17 soldiers were killed and 30 others wounded in an attack on a military base in the central town of Nampala.

National mourning

Mali’s President Ibrahim Boubacar Keita has declared three days of national mourning in a tweet following the latest attack.

The fight against extremist groups is one of the major challenges of Mr Keita’s government.

But a new report by Human Rights Watch says the Malian government is not doing enough to protect civilians from the militants.

Wednesday’s attack shows that even soldiers aren’t safe, says the BBC World Service Africa editor James Copnall.