Naomi Watts and Liev Schreiber are reportedly expecting a baby, with Watts just entering her second trimester.

In Touch Weekly magazine broke the story, with a source telling the publication: "This wasn't planned, but Naomi and Liev are thrilled."

The Australian actress, 38, and Schreiber, 39, have been dating for almost two years.

"They'll probably be married before the baby is born," the source said.

No official statement has been released by the couple.

Last month, King Kong star Watts stepped out in Venice with what appeared to be a baby bump.

Although nothing has been confirmed by her people, Watts, who is in talks to star in a remake of the Alfred Hitchcock classic The Birds, has made no secret that she wants to have children.

"I wish it could have happened a little bit sooner," she has said.

"I have wanted a family since I was 19 - certainly to have children."

Schreiber has landed a recurring role in CSI: Crime Scene Investigation but he also appeared in The Manchurian Candidate and the The Painted Veil, alongside Watts and Edward Norton.