Australia has been accused of using a loophole to back out of a promised emissions cut nearly eight times greater than the combined annual fossil fuel pollution released by the rest of the Pacific.

The prime minister, Scott Morrison, arrived in Tuvalu for the Pacific Islands Forum on Wednesday, facing calls that he take steps to quickly reverse Australia’s rising greenhouse gas emissions, including moving away from coal.

Pacific leaders are also urging Australia to drop its plan to use an accounting loophole to meet the emissions reduction pledge it made at the 2015 Paris climate conference.

Enele Sopoaga, Tuvalu’s prime minister, told the ABC that Australia’s commitment to spend $500m from the existing aid budget for climate resilience and adaptation in the Pacific was a good gesture, but ultimately immoral if it was meant to stop countries talking about the need to cut emissions.

Analysts say so-called “Kyoto credits” that Australia wants to use to help meet its target do not represent additional emissions reductions or help meet the Paris goal of limiting global heating to as close to 1.5C as possible. Instead, they are a fudge that cuts what Australia needs to do to meet its 2030 emissions target roughly in half.

The Australia Institute, a progressive thinktank, compared the scale of the loophole with the emissions released by other countries at the Pacific Islands Forum.

The Morrison government says it will use Kyoto credits equivalent to 367m tonnes of carbon dioxide to help meet its 2030 target (a 26-28% reduction below 2005 levels). By comparison, the combined annual fossil fuel emissions from the other 16 forum members, including New Zealand, is about 45 million tonnes.

Richie Merzian from the Australia Institute said Australia’s plan was an insult to Pacific leaders and undermined the region’s efforts to address the climate crisis. He said the institute’s analysis illustrated why Morrison faced heavy criticism in the lead-up to the forum.

He said other developed countries, including New Zealand, Britain and Germany, had ruled out using the credits.

“Scott Morrison has a choice. Australia can be a leader in the region and a partner in combating the impact of climate change or we can continue to completely undermine any efforts by our Pacific partners by using these dodgy credits,” he said.

Unlike carbon credits created through offset projects such as tree planting, Kyoto credits do not represent an additional reduction in carbon dioxide.

They have been created under the Kyoto protocol, which is set to expire next year. Under that agreement, developed countries set their own targets. For Australia, that was an 8% increase in emissions between 1990 and 2012, and then a 5% cut compared with 2000 levels by 2020.

These targets have been criticised as being not up to what scientists say Australia needs to do to play its part in addressing the climate problem.

The government says Australia did better than its first-stage Kyoto target and is on track to beat its low 2020 target. Under the rules of the Kyoto protocol, it can choose to claim credits equivalent to the amount of emissions by which it beat its target.

But analysts say the idea behind Kyoto credits was to encourage countries to set ambitious targets and strive to beat them. In reality, they have been used to help countries do less.

They say Australia has access to the credits only because it set what have been widely described as unambitious targets.

Merzian said other OECD-member countries had ruled out using Kyoto credits to meet targets under the new Paris agreement, which officially begins in 2021.

It is still unclear how Kyoto credits will be treated under the Paris deal. Governments are expected to explain how they will meet their targets and, unless there is unanimous agreement to ban them, Australia could just potentially choose to include them. Observers say a decision to do this would be likely to spark increasing criticism at climate talks.

The Paris agreement says countries will do more to cut emissions over time, and set targets that reflect their “highest possible ambition”. Analysts says Kyoto credits breach this part of the agreement as they transparently weaken a country’s ambition.

The government has defended the use of Kyoto credits as part of its “responsible, achievable and balanced commitments” to reduce emissions and said it had a strong track record in meeting and beating climate targets.