Six Senegalese soldiers have been killed in an ambush near the country's border with Guinea-Bissau.

The soldiers were returning from patrol late Friday when Senegalese stepped in to attack them.

The ambush is believed to have been carried out by rebels from the Casamance Movement of Democratic Forces in one of the deadliest attacks against Senegalese troops in recent years.

Six soldiers were killed and three injured in the ambush in the Niagha district along Senegal's border with Guinea Bissau.

More than 1,000 civilians have fled the area near the Bissau border and are camping along the national highway toward Ziguinchor, the regional capital, which is about 120 kilometres from the fighting.

The Casamance Movement of Democratic Forces come from Senegal's southern district, which is separated geographically from the rest of the country by Gambia.

The group was originally begun as a separatist movement, fighting for greater autonomy from the government in Dakar.