A UN group of experts has issued guidelines to assess the credibility of commitments by local authorities and businesses to cut their greenhouse emissions to net zero.

The group released the guidelines on Tuesday at the COP27 climate conference in Egypt.

The United Nations launched the group to draw up criteria for assessing non-state actors' targets to achieve net zero emissions by 2050.

The group recommends that they "should set initial targets within a year of making their pledge" and "have short-term targets of five years or less, with the first target set for 2025."

It says targets must include emissions cuts from an actor's "full value chain and activities."

In the case of local governments, targets must include all territorial emissions for cities and regions.

The group recommends that non-state actors should "annually disclose their greenhouse gas data, net zero targets and plans for, and progress towards, meeting those targets" in order to improve transparency.

It says they "must have their reported emissions reductions verified by independent third parties."

UN Secretary-General Antonio Guterres said, "We must have zero tolerance for net-zero greenwashing. Today's Expert Group report is a how-to guide to ensure credible, accountable net-zero pledges."

Surveys show that nearly 1,500 businesses around the world and many local governments have set net-zero goals. But some pledges are less credible than others.