European carbon price plummets to less than $A4 per tonne

EUROPE'S carbon price fell by almost 30% to less than $A4 per tonne on Tuesday night (AEST), sparking Opposition claims Australia's carbon tax was "out of line with the rest of the world".

At one point on Tuesday night (AEST) the European price was down 43% after the European Parliament rejected an emergency plan to make companies pay more for polluting.

Opposition climate change spokesman Greg Hunt said Australia's fixed carbon price of $23 per tonne was now 5.5 times higher than Europe's floating tax.

Australia's carbon price will move from a fixed price of $25.40 in 2015 to a floating price in line with world markets, including Europe.

Mr Hunt said Treasury modelling was forecasting a carbon price of $37 per tonne by 2020.

"Either the government's modelling is correct and we will be even more out of line with the rest of the world, or if it is not, the ALP's carbon tax will face a multi-billion-dollar black hole and the deficit will only get worse," Mr Hunt said.

"The government has to say whether they stand by their revenue figures and modelling."

The Coalition remains committed to repealing the carbon tax if it wins the September 14 election.