The Australian Workers Union (AWU) has backed the Government's carbon price plan, despite earlier threatening to withdraw support if it cost "one job".

AWU secretary Paul Howes says the issue is difficult to deal with because many of his members work in the emissions intensive industries such as steel, aluminium, glass and cement.

Saying the union takes job security of members as the "number one priority", Mr Howes says a plan to cut carbon emissions, however, is "inevitable".

"We said quite rightly and quite proudly that our union would not support a price on carbon that cost the jobs of our members," Mr Howes told reporters after a meeting of AWU officials in Sydney.

But he says the officials believe the Government's plan - which includes a $300 million package to safeguard the jobs of steel workers - addresses the concerns of the union.

"We believe the Government has developed a package which ensures that jobs won't be lost in emissions-intensive trade-exposed industries as we make the transition to a low carbon future," Mr Howes said.

He says the compensation levels to industry are what the union asked for during negotiations with Government and that steel is impacted so much from the high dollar and poor trade results that the industry cannot afford to pay a carbon tax at all.

"That's why we were especially pleased to see the Government announce 94.5 per cent compensation for steel and then guaranteed an additional $300 million in funding for the steel industry over four years," he said.

Mr Howes says the combination of payments means that steel won't, in effect, have to pay any carbon price: "That is what we asked for. That is what was delivered."

"Therefore our union will support the introduction of the carbon price as outlined by the Government," he said.

He warns employers there is "no excuse" for any worker to be laid off under the pricing mechanism, saying the union will "hold to account" any company which attempts to lay off AWU members "under the guise of this tax".

Mr Howes blames the high dollar, "rampant dumping" and increased trade liberalisation for creating a "perfect storm" problem for manufacturers.

"We are concerned about its future and that's why the union will continue to campaign on the issue of saving the Australian manufacturing industry," he said.

Mr Howes says his members are very disappointed in Opposition Leader Tony Abbott's promise to vote against the steel industry support package.

"It's incumbent on him to live up to his promise and be a man of his word and vote for the steel industry transformation fund."