Australian Greens Leader Christine Milne says the Liberal Party's push to remove the charitable status of environment groups amounts to an attack on democracy.

"This is an extension of the Abbott government's ideological attack on the environment," said Senator Milne.

"Tax deductibility should apply to all groups that benefit the community and it's not fair for the Liberals to blacklist environmental groups just because they don't like what they stand for.

Tony Abbott's government must not cave into pressure from the miners to defund legal rights groups, say the Australian Greens.

Australian Greens spokesperson for legal affairs Senator Penny Wright has written to Attorney General George Brandis urging him to resist calls from the mining lobby to defund the Environmental Defender's Office.

"The Environmental Defenders Office is the only thing standing between state governments and a rubber stamp for mining approvals," Senator Wright said.