The helicopter was carrying 20 people, including four crew, when it plummeted into a mangrove forest in the southern coastal area of Missirah on Wednesday night.

What caused the crash is unclear.

Army spokesman Abdou Ndiaye told AFP the death toll had risen from six to eight overnight while three of the 12 injured remained in a serious condition.

The director of the Kaolack hospital in central Senegal told the public APS press agency that some of the injured had been transferred to the capital, Dakar, for treatment.

Authorities have launched an enquiry to determine the cause of the crash.