The star of 90s hit film Jurassic Park has hit out at the Australian Government for failing to legalise same-sex marriage.

Sam Neill said he was in disbelief that equal marriage wasn’t yet legal Down Under, in an interview on the Today show.

The New Zealand-born actor, who is filming in Queensland for a new installment of Thor, attacked parliament’s indecisiveness on an issue that nearly two-thirds of Australians support.

“I can’t believe we’re talking about this at all,” he said in the interview.

“64 percent of Australians are for marriage equality, most politicians are for marriage equality. I don’t think it’s any business of anyone’s who should get married and who shouldn’t.

“Why don’t they just get up and pass the bill? What’s the matter with this constipated parliament?”

Earlier this week, Labor leader Bill Shorten announced his party would oppose a plebiscite on the issue, calling it “divisive”.

He said: “Why should gay people in Australia have to go through a law making process that nobody else does?

“Who do their relationships have an opinion poll.”

Without the party’s support it’s unlikely the bill will pass parliament and will require parties to come together and find a new way forward.

Prime Minister Malcolm Turnbull is likely to face opposition from his own Coalition partner’s the Nationals, who threatened him against a free vote in parliament.

Watch Sam’s response below: