Tony Abbott has confirmed that his government has abandoned its longstanding policy to reduce Australia's emissions by between 5% and 25% of 2000 levels by 2020 – a crucial and internationally scrutinised goal that had retained bipartisan support since 2009, throughout Australia's tumultuous political debate over climate policy.

Asked whether the Coalition still supported the target range as UN climate talks began in Warsaw without any political representation from Australia, the prime minister told journalists: “Australia will meet our 5% emissions reduction target, but this government has made no commitments to go further than that. We certainly are in no way looking to make further binding commitments in the absence of very serious like binding commitments from other countries, and there is no evidence of that.”

In fact, Abbott and the environment minister, Greg Hunt, have regularly repeated a Coalition commitment to increasing Australia's emissions reduction target to up to 25% under a specific set of conditions for global action set down in 2009 and accepted by both major parties.

A recent report by the Climate Change Authority – the independent advisory body set up by the former Labor government – found that the conditions for a target higher than 5% had already been met, and when compared with the actions of other countries, 5% no longer represented a "credible option". The authority – which the Coalition intends to abolish – said a tougher target would be required but did not nominate the target Australia should now adopt in its draft report.

But when asked whether he remained committed to the target range, which Australia has inscribed in its commitments to several international agreements, Abbott said: “We have made one commitment and one commitment only, which is to reduce our emissions by 5% … we have never made any commitments, any commitments to any binding targets over and above that, in the absence of absolutely clear evidence that other countries are going to take a very serious like approach.”

The issue of Australia’s negotiating stance at the Warsaw talks, where its delegation is being headed by the ambassador for the environment, Justin Lee, has been the subject of lengthy discussions at the past two cabinet meetings, most recently on Monday night.

It is unclear whether negotiators will formally withdraw Australia’s target range of 5% to 25%, even though the prime minister has now made it clear both publicly and privately that Australia will not move to a higher target for 2020 and is very sceptical about taking on a higher target in a negotiation for a post-2020 agreement.

The Abbott government has said it will provide only $3.2bn for Direct Action – an amount independent modelling has found will be insufficient to meet even a 5% target – and no more money will be forthcoming. And independent modelling has found that meeting a higher target using Direct Action would be hugely expensive.

The range of targets and conditions under which Australia's target would be raised above 5% were repeated by Hunt in an article for the Australian Financial Review as recently as 30 September, in which he said "the Coalition is committed to a target of a 5% reduction in emissions and the conditions for extending that target further, based on international action".

In a speech to the Grattan Institute think tank in July, Hunt said "we also accept, and we gave support to the government for the targets, not just the 5% but also the conditions for change ... we accept the targets, clearly, categorically, absolutely".

Abbott stated the Coalition's commitment in a letter to former prime minister Kevin Rudd in December 2009, subsequently released under freedom of information laws, in which he requested information on the costs of the proposed emissions trading scheme, but also wrote "the Coalition's position of bipartisan support for emissions reduction targets – subject to the conditions that were earlier outlined – remains unchanged".

Guardian Australia also reported last week that Cabinet was also rethinking Australia's involvement in the Green Climate Fund, an international fund to help developing countries cope with the impact of climate change.

Abbott confirmed that the government would be making no further commitments of funding to the Green Climate Fund.

Labor's environment spokesman, Mark Butler, said: "It's no real surprise to see Tony Abbott walking away from his earlier support for Australia's commitment to reduce carbon pollution by a minimum 5% by 2020 with a higher target range subject to certain conditions. He's made it clear on a number of occasions that he sees no particular problem with carbon pollution.

“This week he hopes to abolish the legislated cap on Australia's carbon pollution and allow the big polluters open slather in the future. And he's got no policy to put in place that has any prospect of actually bringing our carbon pollution down.”

A spokesman for the Australian Conservation Foundation said: “Abandoning the commitment Australia has repeatedly made to the international community to increase our target to 25% would make Australia a deal wrecker.

“Abandoning the election commitment to reduce pollution by 5%–25% wilfully ignores the fact that Australians want more action on climate change, not less, regardless of how its achieved.”