Any move by the Coalition to narrow the definition of what constitutes an "environmental organisation" – and strip them of their charitable status as a result - would represent an "attack on Australian democracy", legal experts have warned.

Donors to 600 Australian environment groups, including Greenpeace and the World Wide Fund for Nature (WWF), face losing the right to deduct donations from their tax as a parliamentary committee investigates the register of organisations administered by the federal environment department.

The campaign highlights potential short -term benefits from mining activity without acknowledging the very real health costs that come with coal. Credit:Nic Walker

Campaigners believe the inquiry is being driven by the mining industry. It was announced in March after a number of state-based Minerals Councils began publicly agitating for the charity status of environment groups to be revoked following effective campaigns against threats to the Great Barrier Reef, the coal seam gas industry and Queensland's mega expansion of coal mining.

They believe there is a political edge to the inquiry because the government has chosen to focus on the estimated $90 million returned to individuals for donations to environment groups rather than the $1.6 billion in deductions associated with churches and the big welfare charities and aid agencies.