Stallone's lawyer Martin Singer said on Thursday that a woman had 'filed a police report alleging a rape that occurred 27 years ago'.
'My client categorically disputes the claim,' Singer said in a statement.
Singer also claims Stallone planned to file a claim that the accuser had filed a false police report.
Law enforcement have confirmed they were investigating a complaint that was made against the 71-year-old actor.
'We got a complaint that was made in November of alleged sexual misconduct in the 1990s,' Santa Monica Police Department spokesman Saul Rodriguez told Reuters. 'We are looking into it and will gather information and whatever we discover will be passed to the district attorney.'