Sylvester Stallone is being investigated over an allegation of sexual assault.

The 'Rambo' actor has been accused of an unspecified incident that allegedly took place in the 1990s and the accusation - which was reported to the Santa Monica Police Department - is currently being reviewed by the Los Angeles District Attorney's office, their spokesperson Greg Risling confirmed to CNN.

But the 71-year-old star's lawyer, Martin Singer, has maintained his client's innocence and slammed the DA's office for making the case public, accusing them of trying to appease ''the #MeToo generation.''

He told the New York Post newspaper: ''The DA's office in both New York and LA want to get it out there that they're investigating these matters.

''You don't see police or the DA's office issuing statements about everybody who files a police report -- people would get ruined.

''Why go to the media? Why not do the investigation first?''

The lawyer maintained the 'Rocky' star had a consensual relationship with the alleged victim, explaining the pair met in Israel when Stallone was filming 'Rambo III' and saw one another regularly for a number of years.

He said: ''They had a consensual, sexual relationship when he was single. But nothing happened.''

And the lawyer claims there are two witnesses who dispute the allegations, which the woman is said to have taken to an online outlet - who declined to publish following the Harvey Weinstein scandal before she reported her ex-lover to police.

He said: ''Two witnesses came forward and disputed her story.

''One was her boyfriend who had been with her for over 10 years. He said she only said the best things about Stallone, told him he was the greatest guy. The only thing that ever upset her was that he slept with someone who worked with him...

''Two third-party witnesses went to the police and then came forward to us and confirmed that story was completely false. The woman had stated how much she liked my client and what a great relationship she had with him -- so it's just not right.

''It's not appropriate for anyone to file a police report because you wanna get a story out in the media. It's totally wrong.''

The legal expert also pointed out that the statute of limitations has already passed on the allegations.

He said: ''The woman knew that even if her story was true -- which it's not -- it's too late to file charges.

''That's not saying people shouldn't file police reports, it's just improper to first try and get a story.''

In 2016, California ended the statute of limitations on some sex crimes but the revised law applies only to crimes committed after January 1, 2017, and offenses for which the statute of limitations had not expired by that date.

A Los Angeles County task force that investigates possible sex crimes in the entertainment industry has been charged with reviewing the case.