LOS ANGELES (AFP) - The on-off girlfriend of American actor Jim Carrey has died at her California home of an apparent suicide, the police said on Tuesday.

"Cathriona White, 30, was pronounced dead by paramedics Monday evening," Fred Corral, a spokesman at the Los Angeles County coroner's office, said.

He said White's death was being treated as a suicide.

Local news reports said the couple, who had been dating on and off since 2012, broke up last Thursday.

White sent a cryptic message on her Twitter account that day that read: "Signing off Twitter, I hope I have been a light to my nearest and dearest."

Carrey, 53, said in a statement that he was "deeply saddened by the passing of my sweet Cathriona". "She was a truly kind and delicate Irish flower, too sensitive for this soil, to whom loving and being loved was all that sparkled," he added.

"My heart goes out to her family and friends and to everyone who loved and cared about her. We have all been hit with a lightning bolt."

White was found at her home on Monday evening by a friend who called emergency services. She had reportedly left a note.