By Peter Bowes BBC News, Los Angeles

Indiana Jones star Harrison Ford turned 60 on Saturday 13 July.

Sometimes described as America's favourite actor, Ford's landmark birthday came as he prepares, once more, to take on his signature role as the swashbuckling hero.

It is more than 20 years since Raiders of the Lost Ark, the first in the Indiana Jones series, was released. It was followed by the Temple of Doom and the most recent instalment, The Last Crusade, in 1989.

Ford was 38 when the original movie was made. Filming of Indiana Jones 4 is scheduled to start in May 2004 with a release date during the 4 July holiday the following year.

"The audience will understand and appreciate that Indiana Jones has grown older," explains Ford. "He'll still be Indiana Jones - finding himself in the same kinds of dilemmas. I don't think it's a problem.

"I personally don't think growing older is really much of an issue," he adds.

Sequel doubt

People's choice: Ford remains a popular actor

Director Steven Spielberg and George Lucas, who is writing and producing the film, are officially on board to make the new adventure.

However, the status of the script remains in doubt. Despite reports that major sections of the story - such as bringing Ford's archaeologist character back as a father - have been completed, the Hollywood veteran says there is still no guarantee the movie will be made.

"We have an ambition to make the film," he explains.

"But unless we get a script that we're all happy with it won't happen. I'm very happy about the fact that we're all committed to a certain idea and we're developing it and hoping that it will be fruitful."

Graffiti break

Harrison Ford has made over 40 films. At one stage during the early years of his career, he gave up acting to be a carpenter. He had appeared in a number of insignificant movies during the late 1960s - and also had a few TV roles - but instant success eluded the aspiring star.

By today's standards he was already an old man when he got his first big break. He was 32 when his performance in American Graffiti set Ford on the road to stardom. His position as a major international celebrity was confirmed when George Lucas cast the rising star as Han Solo in Star Wars.

The way he was: Harrison Ford in Star Wars

"I came to be an actor when I didn't know very much about it at all," explains Ford.

"I hadn't studied acting, I didn't understand film, I wasn't a film-goer, so thankfully I was given enough time in the trenches to learn something about the business."

Producer credit

Ford's next movie, K-19: the Widowmaker, is about Russia's first nuclear-missile carrying submarine. The actor also has an executive producer credit on the movie, which marks a new direction for the star. He has previously shied away from taking on producing or directing duties.

"It's just a question of how much time you want to devote to the process before you change hats and come on stage as an actor," he says.

"In the past I often relied on the studio development process to bring me scripts and now I think the way the business works now is much different.

"In order to get the kinds of projects that I want and twist them into the shape I think they should be in, I have to take a little bit more responsibility and I'm willing to do that," he explains.