Only one shot from the set has been released to the media

The actor has returned to the role 18 years after the last instalment in the franchise, but producers say he is still performing his own stunts.

"He's doing them," confirmed Kathleen Kennedy, one of the film's executive producers. "He just has a few more ice packs and a few more massages."

The fourth film, co-starring John Hurt and Shia LaBeouf, is due in May 2008.

The cast have just completed the first of three weeks of filming in Hawaii, where scenes set in a South American rainforest are being shot.

Some of the movies biggest action scenes will be shot there, with producer Frank Marshall comparing one set-piece to the thrilling truck chase in 1981's Raiders Of The Lost Ark.

"It's that level," he told the Associated Press news agency.

Long wait

Ford, who was 38 when he first donned Indiana Jones' trademark fedora and bullwhip, turned 65 on Friday.

The star, along with producer George Lucas and director Steven Spielberg, had resisted making a fourth instalment in the action series for several years.

Saying they wanted to wait until the script was good enough, the trio held out for over a decade before they were happy.

Kennedy said the movie, which has yet to receive a title, retained all the hallmarks of its blockbuster predecessors.

"The cleverness, the humour and the tone of Indiana Jones is very much alive and well in this movie," she said.

Marshall added that the cast and crew were having "a great time" in Hawaii.

"Nobody's worried about their careers anymore," he said.