A former girlfriend of Charlie Sheen is suing the actor for assault, negligence and emotional distress, claiming they had sex at least five times before he revealed he was HIV-positive.

Scottine Ross, 26, who said she met Sheen while she was working as a porn actress and later became engaged to him, also claimed the actor forced her to have an abortion after she became pregnant in 2014, and that he had kicked and choked her on numerous occasions during their one-year relationship.

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The lawsuit, filed in the California Superior Court, is the first known legal action against Sheen since he revealed in a TV interview in November that he had been diagnosed HIV-positive four years ago.

The former star of TV comedy Two and a Half Men, said he had decided to speak out because he had paid about $US10 million ($A13.62 million) to people for their silence.

Sheen’s lawyer, Martin Singer, said on Thursday that the actor plans to “vigorously defend” the lawsuit filed by Ross.

“We are confident that Mr Sheen will prevail in this action.”

Under California’s criminal statute, a person who knowingly exposes another to HIV through unprotected sex must be proved to have had a deliberate intent to infect them.

The law means that criminal prosecutions are rare but civil cases can be brought on a range of grounds, including alleged negligence, emotional distress or sexual battery.