The bill passed through the Upper House last week in a conscience vote, 23-17.

Western Victoria MP and Democratic Labor Party Leader Peter Kavanagh yesterday asked Governor David de Kretser to withhold Royal Assent on the bill.

Mr Kavanagh said the bill, which would legalise abortion up to 24 weeks' gestation, was not passed through parliament properly.

"There are good reasons to conclude that the Abortion Law Reform Bill 2008 contravenes Victoria's Charter of Human Rights and Responsibilities Act 2006," he said.

"I have been supported by a legal opinion. Under this bill a category of human beings' lives means nothing."

Mr Kavanagh spent three hours in parliament last week stating his opposition to the bill.

He found the method of aborting a baby at 24 weeks particularly disturbing, particularly if babies did not get pain relief.

"What they were doing in America a few years ago was partial birth and abortion, which has since been made illegal," he said.

"What happens is the baby is killed as it is being born. In parliament there was an amendment to ban partial-birth abortion but it was rejected.

"I find that outrageous and disgusting. The pain these babies go through is worse than you could imagine."

Mr Kavanagh's fellow south-west MPs Denis Napthine, Terry Mulder, John Vogels and David Koch rejected the bill, while Labor's member for Western Victoria Gayle Tierney voted in favour of the reform.

Governor de Kretser was yesterday unavailable for comment.