Coal, gas projects 'sticking point' for Greens

The proposed mechanism would cap the emissions of Australia's 215 biggest polluters and companies that breach the limit would be forced to buy carbon offset credits or trade their emissions with other firms.

When asked if the Greens would block the legislation, Mr Bandt repeatedly refused to confirm if his party would vote with the coalition and oppose the changes.

"We've moved significantly towards the government's position even though we don't agree with it," he told ABC radio on Thursday.

"We've said we are prepared to shift, the ball is now in the government's court. This key question of new coal and gas mines is proving to be a sticking point"

The Greens have been slammed by the government, industry and unions, who accuse the party of grandstanding and threatening to leave the country without a functioning climate policy for another generation.