Vin Diesel has apparently joined the cast of Guardians Of The Galaxy.

The Fast And Furious star has posted a picture of alien Groot, a giant living tree, on his Facebook page. Despite there being no caption fans quickly assumed he will voice the role in James Gunn's big-screen version of the Marvel comic.

Vin has been dropping hints on social media since June when he said the comic book studio had requested a meeting with him.

He then posted a picture of himself in front of an Avengers comic book cover and wrote: "Marvel meeting today... Only the people in the room can tell you what was discussed..."

The actor also told fans at Comic Con he had some "big news" to announce.

Guardians Of The Galaxy already has an all-star cast, including Chris Pratt, Zoe Saldana, Benicio del Toro and Glenn Close.

Jim Carrey and Adam Sandler were previously linked to the role of Groot when it was revealed they were in talks for a supporting voice role.

Vin will next appear in Chronicles Of Riddick sequel, Riddick, which is released on September 6, 2013.

Guardians Of The Galaxy is expected to be released in August 2014.