Los Angeles, July 28 (IANS): Actress Naomi Watts has reportedly refused to work with her partner, actor-director Liev Schreiber in his new TV series "Ray Donovan" because she wants to keep her personal and professional life separate.

Schreiber, who has been in a relationship with Watts since 2005, plays the titular character, a fixer for a law firm to the rich and famous.

"Naomi's made a point of distancing herself from Liev's career, and this is no different. She doesn't like to mix business with pleasure. Besides that, she knows Liev's show doesn't need her help," contactmusic.com quoted a source as saying.

The opening episode of "Ray Donovan" got 1.35 million viewers, making it the biggest premiere in Showtime's history. It has already been commissioned for a second series.

The couple, who has two sons, Sasha, six, and Samuel, four, are also believed to have made an agreement with each other to avoid starring together on screen.

The actress, who will next be seen playing Princess Diana in the film "Diana" is determined to stick to the agreement because she wants to keep the romance alive in her marriage.

"Naomi's not going to budge. She believes working on the show would kill their romance and she thinks Live will thank her one day for turning him down," she added.