Michael J. Fox has been reunited with his Back To The Future co-stars 33 years after making the first film in the trilogy.

A photo posted on Instagram showed the actor, who found fame playing teenager Marty McFly in the time-travelling franchise, with cast members Lea Thompson, Christopher Lloyd and Thomas Wilson.

The snap was taken at the Fan Expo Boston convention and was shared by Thompson, who played Marty’s mum.

“Four old friends get back from the future,” she said.

Lloyd, who starred as inventor Dr Emmett “Doc” Brown, shared the same picture and wrote: “This was special.”

“Wow. This just happened.” said Wilson, who played the trilogy’s villain, Biff.

The cast took part in a panel discussion where they addressed speculation that a fourth film could be on the cards.

According to reports from the convention, Wilson joked: “Basically, I think America is saying, ‘Come on they’ve wrecked every other franchise with bad sequels, why not this one? C’mon, we would watch it until it sucks’.”

However, Fox, who was diagnosed with Parkinson’s disease in 1991, told the crowd that co-creator Bob Gale is the “gatekeeper of the franchise”.

Both Gale and director Robert Zemeckis have previously indicated that another Back To The Future film is unlikely.

Back To The Future was released in 1985 and sequels followed in 1989 and 1990.