Defence Minister Robert Hill today said it was unfair to drag up after more than two decades, a charge of sexual assault against Health Minister Tony Abbott.

The Age newspaper today reported that Mr Abbott was charged with indecent assault 27 years ago when he was a 20-year-old university student leader.

Mr Abbott told the paper the charge was dismissed in January 1978 after the magistrate complained of ''enormous conflict'' between the prosecution and defence evidence.

Senator Hill said it was unfair the case had been dragged up again.

''I do think it's pretty rough justice when you read the small print and you find that this allegation, made at some sort of student rally 27 years ago, was dismissed by the magistrate,'' Senator Hill told Network Ten.