The federal government is facing resistance from the states over its request for caps on coal prices, as it races to finalise the details of a market intervention to curb skyrocketing energy costs.

As revealed by the ABC, the government is set to cap gas prices at around $12 a gigajoule and force companies to set aside a certain amount of gas for domestic consumption.

But as the nation's leaders prepare to meet on Wednesday, the prospect of capping coal prices is proving more problematic.

New South Wales Treasurer Matt Kean has confirmed the federal government asked the states to impose their own caps on coal, and even recall their parliaments to make any legislative changes required.

Mr Kean said NSW had sought legal advice confirming the Commonwealth has the power, in the constitution, to cap prices.

"They've said that they'd prefer the states to do this … but this is a national problem, that requires a national solution," he told Sky.

"You can't have every state and territory going off and doing their own thing."

When asked directly if he supported a temporary cap on prices, Mr Kean said "if the Commonwealth wants to go down that path, then obviously we'd support it".

However, Mr Kean said it was important that gas and coal prices were capped, noting coal had risen from about $100 a tonne to $600 a tonne since Russia's invasion of Ukraine.

"In NSW and Queensland, black coal sets the wholesale electricity price more than 50 per cent of the time," he said.