Oksana Grigorieva and Mel Gibson Split

FILE - In this Wednesday, Oct. 5, 2011 file photo former British Prime Minister Tony Blair speaks at the Cuyahoga Community College scholarship luncheon in Cleveland. Prime Ministers come and go, but News Corp. chief Rupert Murdoch stays and stays and stays. Murdoch has played a key role in shaping political British political coverage for the last four decades, and testimony at the Leveson inquiry into media ethics has highlighted how prime ministers have both courted and feared the 81-year-old media mogul. (AP Photo/Mark Duncan, file) / Mark Duncan

Mel Gibson and girlfriend, Russian musician Oksana Grigorieva, have split after over a year of dating, a source told People magazine Wednesday.

"They just drifted apart," says a close friend of the couple of the amicable split. "They're both working hard on their careers and trying to raise a sweet baby together. They're still friends and they'll both raise [their daughter] together."

Photos: Celebrity Splits

The two welcomed daughter Lucia on Oct. 30, 2009.

Gibson has seven children with his estranged wife, Robyn, who filed for divorce from the actor in April 2009 after nearly three years of separation. Grigorieva also has a son from a previous relationship with ex-boyfriend Timothy Dalton.