A former Newbury Weekly News reporter, now freelancing with his own PR firm, had a run-in with security guards when he tried to take photos of Sienna Miller at Niagara Falls.

Nigel Morgan, a former chief reporter at the paper, was on holiday and visiting Niagara when he spotted the celebrity on the set of her new movie.

But he found himself threatened with arrest after taking photos of the British actress.

He said: "People were complaining that the film crew had taped off the best spot for viewing the falls; especially for an 'unknown' actress."

"But even with her lurid red wig on I spotted Sienna."

"Along with 300 other tourists I was taking photos, when this bear-like security guard lumbered up and ordered just me to stop taking pictures. He first claimed I was putting off the actors and then that I was stealing their intellectual property!

"I countered that they were surely filming in a public area, but he growled if I didn’t stop he’d call over the police who were nearby, they’d arrest me and explain it 'downtown’.

"So I pre-empted him and called a couple of nearby officers over – and they quickly reassured me I was free to take photographs.

"The security guard just glowered and wandered off leaving me free to take photos – it was then the police asked me if I knew who the actress was? Clearly Sienna is more famous in our tabloids that across the Atlantic."

The actress was filming 'Camille’ with actor James Franco, a black comedy due out in 2007.

The falls are a favourite of movie makers, and were made famous as a film location by Marilyn Monroe in 'Niagara' in 1952. They have since been the setting for such films as The Long Kiss Goodnight, The Whole Nine Yards and Bruce Almighty.