The Victorian Greens are calling for a parliamentary inquiry into a deal that would extend Crown Casino's operating licence until 2050.

The State Government would reap more than $900,000 from the agreement, which includes an expansion of the gaming floor at the casino.

But the Greens said the legislation meant Crown was entitled to up to $200 million in compensation if any change was made to problem gambling measures or other taxes that might affect the casino's profits.

Greens' leader Greg Barber said the bill must be scrutinised because it was a very good deal for Crown.

"I'm sure other pubs and clubs out there who own the other 90 per cent of poker machines would wish they had the same legislated insurance policy against future governments, til 2050, ever deciding to do something serious about problem gambling," he told 774 ABC Melbourne.

Mr Barber said it was an unprecedented deal.

"If Crown's really worried about this, then what they're telling you is that they know they're making a lot of money out of problem gamblers," he said.

"The more the Government gets involved with the private sector, the more they want to legislate a special compensation trigger to bind future parliaments against any of this kind of action."

Opposition leader Daniel Andrews has refused to say if he would support the idea of an inquiry.

"We're working our way through the bill, every line of it," he said.

"We're doing this in a careful and considered way, as we have done with every bill before Parliament. That's our responsibility. We don't take it lightly."