Four people have been killed in Burundi in a grenade attack on a bar in the capital Bujumbura, officials say.

Among the victims was a child selling boiled eggs. Ten other people were injured in Saturday's attack.

Unknown attackers also threw grenades at an army patrol and at police in Bujumbura, hurting several people.

Since April, more than 400 people have died in clashes triggered by President Pierre Nkurunziza's bid for a third term. He won a disputed poll in July.

The African Union is trying to persuade the president to agree to the deployment of AU peacekeepers.

He is opposed to the plan, saying this would amount to an invasion.

Bujumbura has recently witnessed a string of deadly grenade attacks.

The government and opposition groups have accused each other of carrying out the attacks.

Last month, human rights group Amnesty International published satellite images it said were believed to be five mass graves near Burundi's capital, where security forces were accused of killing scores of people in December.

A fact-finding mission by the AU has reported arbitrary killings, torture and the "closure of some civil society organisations and the media".