The Abbott government is defending its decision to approve Clive Palmer's $6.4 billion coal project in Queensland's Galilee Basin, saying his role in parliament had nothing to do with the outcome.

Mr Palmer's Waratah Coal has been given the green light to build a thermal coal project near Alpha in Queensland's central west, plus a rail line linking the project to a proposed port at Abbot Point.

Environment Minister Greg Hunt on Friday approved the environmental impact statement for the project, publishing his report on his department's website.

Environmental groups slam approval of Palmer's $6.4 bn coal project

The federal opposition has questioned why a government that stresses it is open for business wouldn't even release a media statement about such a large infrastructure decision.

"You'd think that something worth $6 billion would be worth a mention other than a simple addition to a website," Labor frontbencher Bernie Ripoll told Sky News on Saturday.

"It's just strange."

Mr Palmer is the only member of the Palmer United Party in the House of Representatives, but from July a number of senators from his party will take their seats in the upper house.

The PUP vote in the new Senate will be important as the government tries to abolish the carbon and mining taxes, an effort blocked so far by the combined force of Labor and the Australian Greens.

Mr Palmer has campaigned to remove the carbon tax and compensate large companies for their first year payments under the scheme.

His company Queensland Nickel is one of just three firms in Australia that has not paid its carbon tax debt, and is challenging the $6.2 million bill in court.

But the government has denied any suggestion of a question mark over the Waratah Coal decision because of Mr Palmer's role in Australia's parliament.

Parliamentary Secretary Paul Fletcher said the project was considered by the environment minister on its merit alone, in accordance with legal requirements.

"The approval process quite properly is blind to the characteristics of the individual applicant," he told Sky News on Saturday.

"Mr Palmer has to comply with the law of the land like any other citizen."

He said Mr Palmer was an independent member of parliament and the coalition had "no responsibility" for him, adding they had not been briefed by the member for Fairfax.

But the Australian Greens say the decision is a "blessing" for Mr Palmer, and accused the government of quietly sneaking out the decision late on the Friday before Christmas when nobody would notice.

Conservationists deplored the Waratah Coal decision, saying the mine puts the Great Barrier Reef at significant risk and ignores growing warnings about climate change and carbon emissions from coal.

The Greens also took issue with Minister Hunt's approval of the Surat Gas Expansion project, which they claim put Queensland's land and groundwater at risk.