A soldier was killed by presumed separatist rebels in Senegal's troubled southern Casamance region on Wednesday, a day after clashes left three troops dead, a military source told AFP.

"The rebels ambushed one of our units which was carrying out a search operation. There was a confrontation and we lost one man and four were seriously injured," said the source on condition of anonymity.

On Tuesday, three soldiers were killed and another six wounded in fighting with rebels from the Casamance Movement of Democratic Forces (MFDC), in what has been a bloody few months in west Africa's longest running conflict.

"These days there are too many explosions preventing us from attending to our business. Army helicopters and planes regularly bomb suspected rebel positions," said a resident of the area where the attacks took place.

The Casamance is separated from the rest of Senegal by Gambia and the MFDC has fought for independence since 1982.

These days MFDC rebels mostly carry out large-scale hijackings and terrorise villagers, occasionally clashing violently with the army.

The conflict, which has seen periods of quiet and surges of violence, has not reached the levels of bloodshed of other wars in the region but has nonetheless claimed thousands of lives over the past three decades.

Violence soared over November and December with 23 people, including 10 civilians, killed in fighting.

Several peace accords have failed and the MFDC is reportedly riven with divisions.

President Abdoulaye Wade, who promised upon his election in 2000 to solve the crisis within 100 days, visited the region last weekend as he campaigned for a third term in the February 26 poll.

The Casamance unrest has remained a thorn in the side of Wade's regime and during his visit he proposed a plan which involved disarmament, demining and five major agricultural projects.