All federal funding to Environmental Defenders Offices will dry up by the middle of next year, ending 20 years of support.

The government has been accused of giving big miners and developers an unfair hand over communities by slashing all federal funding to Environmental Defenders Offices (EDOs).

EDOs, which provide free advice to communities wanting to mount legal challenges against developments in their area, will lose all federal funding by the middle of the next year.

The shock announcement by the Attorney-General’s Department came on Tuesday, and broadsided EDOs now face the prospect of closing down offices and scaling back case work.

EDO NSW executive director Jeff Smith said he’d signed a contract with the former Labor government for $10 million in funding over four years, but that had been torn up out of the blue.

“Obviously we’re looking at the agreement, but I don’t think there’s much value in exploring that too much,” he told AAP on Wednesday.

Regular funding of about $100,000 a year to EDO offices nationwide has also finished.

Mr Smith said Attorney-General George Brandis had been lobbied heavily by the NSW Minerals Council to strip EDOs of federal funding they’d received for about 20 years.

Tackling the Goliaths on behalf of the Davids wasn’t going to go unnoticed forever, he added.

“I think our biggest problem is we’re highly effective,” he said, adding he’d sought unsuccessfully for a meeting with the Attorney-General.

“When you do the kind of work that we do, where ultimately you are undertaking legal challenges and holding decision makers to account, then that can be quite confrontational.”

Australian Greens senator Larissa Waters, herself a former EDO lawyer in Brisbane for nearly a decade, said the decision was part of a wider push by the Abbott government to erode environmental protections.

She said the government was intent on crippling EDOs and removing barriers for business groups wanting to make profits off the environment.

“I think this will result in developers and big miners being able to get away with a lot more,” Senator Waters told AAP.

“It just indicates that this government is intent on empowering the big end of town and silencing the community.”

Mr Smith said this decision was particularly concerning given the government was unwinding climate action and the Great Barrier Reef was facing unprecedented threats.

EDOs have been highly critical of the government’s “one-stop-shop” for environmental assessments, a proposal agreed to by all states and territories to hand federal approval powers to the states.

Attorney-General George Brandis said the government believed legal financial assistance should be directed to disadvantaged Australians who are most in need of legal assistance

“Rather than using public money on advocacy and lobbying activities,” he said in a statement to AAP.

“It is vital that vulnerable Australians receive the help they need with their legal problems.”