Cillian Murphy has said he knew things were going well in his acting career when people started to pronounce his name correctly.

The Irish actor was speaking at the Sundance Film Festival and revealed how his appearance in Utah nine years earlier to publicise 28 Days Later was the start of big things for him.

Cillian, who is currently promoting the thriller Red Lights, was a breakout star at Sundance in 2003 with the horror hit about a London man who wakes from a coma to find the land overrun by a plague that has turned people into raging zombies.

While the film was already a hit in Britain when it played at the festival, Cillian admitted the rousing reception at Sundance built US buzz for the film and for himself, and he went on to appear in Christopher Nolan's Batman Begins, The Dark Knight and Inception.

"When it was well-received here, that had a big impact on its release in the States," said Cillian, who had a handful of credits behind him when director Danny Boyle cast him in the lead of 28 Days Later.

"I think that was my first time in a film with a real, proper director, a name director. And it was a nice part, so I guess people attempted to pronounce my name after that. That was definitely the watershed."

In writer-director Rodrigo Cortes' Red Lights, Cillian and Sigourney Weaver play researchers who debunk phony claims of the paranormal, while Robert De Niro co-stars as a superstar psychic.

Millennium Entertainment announced that it has picked up the US theatrical rights for the movie.