OSCAR-winning actress Angelina Jolie is pregnant with a child fathered by her long-rumored paramour, actor Brad Pitt, his spokeswoman said this morning.

Publicist Cindy Guagenti also confirmed reports Pitt has filed papers to become the legal adoptive father of Jolie's two adopted children, son Maddox, four, and daughter Zahara, who is about 11 months old.

Guagenti acknowledged Jolie's pregnancy but declined to give further details, including when the baby was due, or to say whether the couple had plans to marry.

Representatives for Jolie were not available for comment.

News of Jolie's pregnancy was first reported today by People magazine, which quoted the actress as telling a charity worker in the Dominican Republic, where she is working on a movie, "Yes, I'm pregnant".

The magazine said the 30-year-old actress is expecting her baby this northern summer.

Pitt, 42, and Jolie met in 2004 while working together on the film Mr and Mrs Smith, in which they played married assassins ordered to kill each other. The movie ends with the two still alive and happily married.

Rumors of an affair heated up after Pitt and his ex-wife, former Friends star Jennifer Aniston, split up in January 2005.

Tabloid reports speculated at the time that Pitt wanted children but that Aniston was not ready for motherhood.

Pitt's divorce became final in October, but he and Jolie have until now publicly denied being anything more than friends, despite recently published photos showing the two spending private time together with her two children.

Pitt also has recently joined Jolie, a goodwill ambassador for the UN refugee agency, in efforts to promote various humanitarian causes, including greater assistance to fight poverty in Africa.

The actor accompanied Jolie to Ethiopia in July when she visited that country to finalize the adoption of her infant daughter. And he traveled with her to Pakistan last month to visit a remote area stricken by an earthquake.

Jolie, who won an Academy Award as best supporting actress for playing a psychiatric patient in Girl, Interrupted, was divorced from actor Billy Bob Thornton in 2003. Before that she was married to actor Jonny Lee Miller, whom she divorced in 1999.

A spokesman for Aniston said the actress would have no comment.

"Jennifer is not in the practice of commenting on the lives of other people," he said.

Asked about news of his daughter's pregnancy, Jolie's estranged father, Oscar-winning actor Jon Voight, told the syndicated TV show Access Hollywood: "Angie is my daughter, and I am always wishing the best for her".