By the BBC's Chris Simpson Dakar

At least five people have been killed in an ambush in the troubled southern Senegalese province of Casamance.

The attack was carried out by guerrillas from the Movement of Democratic Forces of Casamance (MFDC), the authorities say.

For the past 20 years, the MFDC has waged a violent campaign to create a separate state in southern Senegal.

The latest incident happened in the village of Birassou on Monday afternoon, as government ministers were at a local election rally just a few kilometres away in the town of Bignona.

Elusive peace

A group of armed men surrounded a number of vehicles on the road.

Some rebels have not signed the peace deal

Passengers and drivers were robbed, before the gunmen opened fire.

Last year the MFDC leadership signed a provisional peace accord with the government and appeared to have strongly modified its separatist position.

But there has been little follow up to that agreement.

The MFDC is bitterly divided and the movement's weak leadership has little control over distant groups who have kept up their military activities carrying out regular road ambushes and kidnappings.

Promises

The government has responded with troop deployments and counter-offensives, but the security situation in many parts of Casamance remains difficult.

The main political parties are running high-profile campaigns in the south, ahead of local elections on 12 May.

The parties are offering assurances that they will end the conflict and work for peace and prosperity.

Senegal's Minister of Defence, Youba Sambou, was among senior officials attending a meeting near Birassou.