United Nations secretary-general Antonio Guterres has urged countries and companies to tackle climate change, saying failure to do so would mean “economic disaster”.

Speaking at the annual UN climate meeting in Madrid, Mr Guterres said fears that measures to cut greenhouse gas emissions would decimate existing industries ignored the opportunities arising from the “green economy”.

“For too long, vested interests have peddled the false story that economic growth and tackling climate change are incompatible,” the UN chief said.

“This is nonsense.”

“In fact, failing to tackle global heating is a sure-fire recipe for economic disaster,” Mr Guterres added.

He cited a study showing that shifting to a low-carbon economy could create 65 million new jobs worldwide by 2030 and boost growth by 26 trillion dollars.

Scientists say countries need to stop burning fossil fuels by 2050 at the latest to ensure global temperatures do not rise more than 1.5C (2.7F) this century.

“This transition needs to be done to benefit everybody,” he said.

“And not doing this transition will only allow, as I said, the survival of the richest.”

His remarks came as negotiations in Madrid officially entered their final two days, with agreements on key issues still out of reach.

Vulnerable countries expressed outrage over Australia’s bid to hold on to piles of emissions vouchers left over from a now-discredited system that would allow it to meet its climate commitments without reducing pollution.

Talks to agree rules for global carbon markets and aid for poor countries already affected by climate change also made little progress.

Overnight, the UN climate office said it would let dozens of observers who were expelled from the meeting back into the venue.

A demonstrator is surrounded by UN security staff members during a protest at the COP25 summit in Madrid
A demonstrator is surrounded by UN security staff members during a protest at the COP25 summit in Madrid (Bernat Armangue/AP)

Some 100 people were escorted off site on Wednesday after some staged an impromptu demonstration outside a hall where Mr Guterres was speaking.

The protesters said they were angered by the slow pace of the talks and the apparent unwillingness of major greenhouse gas emitters to do more to curb global warming.

The UN climate office said on Thursday that the protesters violated rules they had agreed to in advance to be accredited for the talks, including a prohibition on holding “unauthorised demonstrations”.

In a joint statement, representatives from the various groups said they would abide by the guidelines and seek permission before staging future protests.