Andrew Lincoln has said his Walking Dead castmates are baffled when they hear his English accent.

The Love Actually actor plays police officer Rick Grimes in the American show about life after a zombie apocalypse, and his role requires a heavy Southern accent.

Speaking on the red carpet at the Los Angeles premiere of the fourth series of the show, Andrew said some of his colleagues don't know how to react when they hear his real voice because he maintains his American accent all through filming.

"A lot of cast are here today asking what I'm doing with that accent, it's the weirdest thing. They are a bit freaked out. I get a bit coy around them so I may slip into my dialect."

He added that he speaks in Rick's voice so much, his English accent doesn't feel natural any more.

"This isn't normal any more, I'm American now," he said. "It's a very strange schizophrenic life that I lead and I love it in a strange twisted kind of way.

"Everyone involved in this show has become my family. I uproot my own family and we live in America for most of the year now because of the success of the show.

"I love this character and when you come here you realise the responsibility you have to tell the best story for the fans and I'm interested in exploring all the parts of this man and that is one of the great luxuries of working for four years. I get to be an apocalyptic cowboy for a living."

The new series of The Walking Dead will begin on Fox on Friday October 18 at 10pm.