Schwarzenegger has been pursuing a political career for the last year

Talks are under way for Terminator 3 director Jonathan Mostow to return for a further sequel in the series which made Schwarzenegger a household name.

"We're certainly talking to Arnold and his people," a spokesman for the film's financers, Intermedia, said.

A Schwarzenegger advisor ruled out anything but a cameo role.

Intermedia spokesman Dennis Higgins said Mostow was overseeing the draft of a script by writers John Brancato and Michael Ferris, who wrote Terminator 3's screenplay.

The Terminator series is one of the most successful film franchises ever.

Terminator 2: Judgement Day grossed $500 million, while Terminator 3 took $427 million around the world.

But Schwarzenegger said he would put his film career on hold when he was elected governor of California in November.

Paul Wachter, Schwarzenegger's personal financial advisor, refused to rule out a cameo, but dismissed anything more than that.

He said: "Is it realistic that while he is in office, he takes a starring role? Hardly."