A French secret agent held hostage in Somalia urged President Francois Hollande to negotiate his release in a video shot by his Islamist militia captors, the SITE monitoring group said Thursday.

"Mr President, I am still alive, but for how long? That depends upon you," Denis Allex says in the footage, which SITE said was released by the Shebab, the Somali guerrilla group that has held him for more than three years.