Actor Robin Williams who plays a lonely stalker in his new film has said he himself has been stalked.

In the psychological thriller, One Hour Photo, Williams plays the part of obsessed photograph technician Sy Parrish.

They think you have spoken to them and no-one else Robin Williams on stalkers

The lonely outsider becomes fixated with a young mother and her family, making prints of their photographs for his own private collection.

But in real life the tables have been turned with himself the subject of stalkers over the years.

One schizophrenic woman even arrived at his home making it as far as the gates to his ranch.

'Warning signs'

"Once in a while people show up at your house but you usually get letters beforehand," said Williams at a press conference to promote his new film.

"There are warning signs before they show up.

"I get weird scripts and ideas because I have done such strange characters."

As a celebrity he accepts that this goes with the territory and has security cameras at his home's entrance.

"I have had a few strange people over the years," he said.

But where it becomes an issue is when people believe that they have some kind of special relationship with him.

"They think you have spoken to them and no-one else," he said.

Darker side

He has welcomed his return to the darker side in a succession of roles, which have included Insomnia, where he plays the killer Al Pacino has to hunt down.

With these characters he has found he is no longer bound by the confines of respectability.

The latest role is a far cry from Williams's comic persona

The very fact his public persona is as that "nice man" made his transformation into a killer in Insomnia all the more ugly, he said.

As for One Hour Photo, he said he just "had to do it" because it was "so strange".

He has spent much of the past year touring the US on the stand-up comedy circuit, where he has spoken about the 11 September attacks.

"It was about going back and talking about it in a humorous way to deal with something so awful," he said.

"How do you deal with all this madness?

"The only weapon we have is comedy," he continued.

As to the future, being 51 years old has given him the opportunity to play "character" parts.

Destined

He celebrated his 50th with a party on a private Caribbean island, where he quipped guests had taken part in their own "Survivor" show.

Having recently attended a party for Billy Connelly's 60th birthday, he would love like to work with him, if they could find the right project.

Meanwhile he seemed unconcerned Robbie Williams might be offered parts destined for him, if the pop star made it big in the States.

It could be worse - he is after all a "handsome man," he said.

One Hour Photo, which is a 15 certificate, opens nationwide on Friday.