FILE- In this undated file image from a video posted on islamic militant websites. A man identified as French security agent Denis Allex pleads for his release from the Somali militant group al-Shabaab who have been holding him for nearly a year.

Mogadishu - Somali militants linked to al-Qaeda said on Thursday they had executed a French agent who French armed forces had tried to rescue at the weekend.

The al-Shabaab rebel group said on its Twitter account that Denis Allex, held hostage since 2009, had been killed on Wednesday.

“Let Muslims enjoy his execution and the French cry,” Sheikh Abdiasis Abu Musab, al-Shabaab's spokesman for military operations, told Reuters by telephone.

The militants said on Wednesday the decision to kill Allex was unanimous and followed three years of what it called exhaustive attempts at negotiation.

France has consistently said it believed Allex was killed in Saturday's failed rescue mission and have accused the militants of manipulating the media with their latest statements.

Two French commandos were killed in the failed raid which coincided with the launch of French air strikes against Islamist militants in the West African country of Mali. - Reuters