Wahlberg and fiance expecting baby

Actor Mark Wahlberg is set to become a dad again - his fiance Rhea Durham is pregnant for the third time.

Wahlberg, 36, and longterm partner Durham, 29, have yet to go public with their news - but the Boogie Nights star has reportedly told friends he is expecting a son, due in September.

A friend close to the star tells US magazine OK!: "Mark is thrilled to be having another baby. He is an amazing dad, and his two children are his world.

"He always used to joke about wanting at least a dozen kids, but it looks like he wasn't joking after all."

Wahlberg and Durham - who have been dating since 2001 - are already parents to daughter Ella Rae, four, and two-year-old son Michael.