By Sam Adams PUBLISHED: 04:09 EST, 17 January 2013 | UPDATED: 05:23 EST, 17 January 2013 Terrorists today announced they have executed a French spy who was held captive in Somalia for years - but French authorities say he was already dead. Al-Shabaab, a Somali-based group linked to al-Qaeda, said on Twitter they had killed the agent, codenamed Denis Allex, yesterday at 4.30pm GMT. The group had previously said France had 'signed [Mr Allex's] death warrant' by launching a failed rescue operation over the weekend in which two French commandos lost their lives. Scroll down for video
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Militant group al-Shabab had held French spy Denis Allex since 2009
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Revealed on Twitter they had killed him following bungled rescue attempt
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French commandos had stormed house after arriving in five helicopters
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Group said France had 'signed his death warrant' by launching failed raid
In a statement yesterday, al-Shabaab claimed that Mr Allex, who was kidnapped in July 2009, was alive and had been in another safe house that was not targeted by the @placeholder rescue force.