For many years, Senegal resisted putting Mr Habre on trial but it has changed its position under new President Macky Sall.

BBC: Mahamat Djibrine: Chadians hail ex-police chief's arrest

It followed the defeat of Abdoulaye Wade in the March 2012 presidential election by Macky Sall, who pledged to fight corruption.

BBC: Senegal's Karim Wade charged with corruption

If confirmed, Friday's attack would be the deadliest attack since President Macky Sall came to power in March 2012, according to AFP news agency.

BBC: Four killed in Senegal's Casamance region