A review of DNA evidence has led to a man being charged over two alleged sexual assaults in southwest Sydney 24 years ago.

In March 1989, a 24-year-old woman was picked up by a man driving a car and taken to a bush clearing in Wedderburn, where she was allegedly physically and sexually assaulted.

In November of the same year, a 47-year-old woman was asleep in a caravan in Appin when an unknown man allegedly broke in and threatened her with a knife, before sexually assaulting her.

Both incidents were reported to police and despite investigations, no arrests were made at the time.

However, evidence taken from the scene was submitted for DNA review recently and after receiving the results, detectives arrested a man in Goulburn on Tuesday.

The 51-year-old man was charged with a number of sexual violence offences.

He has been refused bail and will appear in Campbelltown Local Court on April 10.