On Sunday, the army announced that it had launched an operation in the southern region of Casamance, aiming to dismantle bases of Salif Sadio's rebel MFDC faction.

The Movement of Democratic Forces of Casamance (MFDC) has led a low-intensity separatist conflict in southern Senegal since 1982, which has claimed several thousand lives.

However, the Casamance conflict had mostly lain dormant until Senegal launched a major offensive last year designed to drive out the rebels.

In the latest clash on January 24, four Senegalese soldiers were killed and seven were captured alive and taken across the border to The Gambia. The rebels released the hostages the following month.

In a statement seen by AFP on Tuesday, Catholic lay association Sant'Egidio called for an "end to the current military operations conducted by the Senegalese army".

The Rome-based group has acted as a mediator in the Casamance conflict in the past. It contributed to the release of the captured Senegalese soldiers in February, for example.

"It is only through reasonable negotiations that a definitive peace will be possible in Casamance," Sant'Egidio said.

Senegalese President Macky Sall has made achieving "definitive peace" in Casamance a priority of his second term.

Casamance was a Portuguese possession for several hundred years until it was ceded to colonial France in 1888. It became part of Senegal after the country gained independence in 1960.

The region, which has a distinct culture and language, is separated geographically from the rest of Senegal by the Gambia River, around which lies the tiny state of The Gambia.