Australia will cut its funding to the UN Environment Programme (Unep) by more than 80%, it has been reported.

The federal government was due to give $1.2m to Unep this year, but will now give just $200,000. The ABC reported $4m would be cut over the next four years.

The environment minister, Greg Hunt, said the fund was not a budget priority for the government.

“You’ve always got to make choices in a difficult budget environment. I would imagine that most Australians would think that putting $12m into coral reef protection within our region, and combating illegal logging of the rainforests of the Asia Pacific would be a pretty good investment, rather than $4m for bureaucratic support within the UN system,” Hunt said.

Unep was established in 1972 with the aim of promoting environmental sustainability through global action. It relies on contributions from member countries.

“Close to 90% of the financing of Unep is voluntary and depends on countries’ goodwill and also their recognition of Unep,” the executive director of the program, Achim Steiner, told the ABC.

“You have to be disappointed [with the funding cut] because clearly the contribution of member states is what enables the Unep to fulfil its mandate and be of service to the global community,” Steiner said.

The opposition spokeswoman on foreign affairs, Tanya Plibersek, said: “Tony Abbott tried to keep climate change off the G20 agenda, but he failed. That’s because other world leaders know climate change is both an environmental and economic issue.”

“The cuts revealed today just reinforce that when it comes to climate change Tony Abbott is out on his own.”

Based on its funding commitments for 2012, Australia ranked 13th globally in its support for Unep. The Netherlands contributed the most, with $10m. The US pledged $6.5m and the UK $5.7m.

The foreign minister, Julie Bishop, will soon visit Peru for major international climate talks that have been hailed the best chance in a generation for reaching global climate consensus.

The Greens leader, Christine Milne, labelled the funding cut “a slap in the face”. “Australia is a global pariah on the climate front,” Milne said on Tuesday. “This sleight of hand is just extraordinary.”

She accused the government of using money taken from Unep to fund its commitment to stop illegal logging of rainforests, made at the World Parks Congress in Sydney in November.

“This is really Australia on a world stage behaving badly on the climate. We are so out of step as a nation with the rest of the world. We are not only risking the environment, but Australia’s standing in the world is seriously diminished by the Abbott government,” Milne said.