SYDNEY (Reuters) - Actor Mel Gibson and his Russian girlfriend Oksana Grigorieva are celebrating the birth of a daughter, according to media reports.

Gibson, 53, announced in May that his girlfriend was pregnant. Celebrity website RadarOnline.com said 39-year-old Grigorieva gave birth on Friday, a few weeks early. There were no further details.

The Australian-raised actor already has seven children from his first wife Robyn who filed for divorce in April this year after 28 years of marriage. Grigorieva has a teenage son with former James Bond actor Timothy Dalton.

Gibson has said that he and his wife split up three years ago, shortly after he was arrested in Malibu for drunken driving and launched into an alcohol-fueled tirade against Jews. He later apologized and sought treatment for alcoholism.

He told TV talk show host Jay Leno that he met Grigorieva, a former model who is now a singer and pianist, in 2008 when she had been signed to his Icon Records label. Her debut album, "Beautiful Heartache," was released this year.

Gibson was raised in Australia and was one of the highest-paid and most popular actors in the world in the 1990s, winning best-director and best-picture Oscars for his 1995 movie "Braveheart."