Credit: Michael Kovac/FilmMagic

Oksana Grigorieva added a touch of mystery to her sudden split from Mel Gibson during a press conference in Moscow on Monday -- her first outing since last week's announcement.

In her native country to announce a concert for the "Give a Life" charity, the Russian pianist gave a brief explanation about the breakup with Gibson, 54, who is father to her daughter Lucia, 5 months.

"I can tell you that..we have split up, suddenly and recently," Grigorieva said. "Unfortunately, I cannot give you the reason. But you will find out everything quite soon."

The musician continued, "Here is the official version: We split up by mutual consent and we will raise our daughter together. She is currently with my mother in my Los Angeles home."

One casualty of the breakup: a hammer-and-sickle (i.e. the communist symbol) tattoo on the singer's ankle, which Gibson had suggested for her. Grigorieva confirmed to reporters that she is removing the stamp.

"No one dumped anyone," a source told Us of the breakup. "It's all very friendly."

Gibson filed for divorce from his wife of 28 years, Robyn, last April. They are parents to seven children. The couple were worth $900 million and it was believed to be the most expensive divorce settlement in Hollywood history.

Grigorieva has a son named Alexander with her ex boyfriend, actor Timothy Dalton.