Washington on Wednesday joined China in stressing that the present accords, such as the landmark 2015 Paris Agreement, were the best way to tackle the climate crisis, but their comments draw fury from campaigners.

The UN climate change regime "embodies the clearest, most specific, and the most current expression of states' consent to be bound by international law in respect of climate change," said Margaret Taylor, legal adviser at the State Department.

"Any other legal obligations relating to climate change mitigation identified by the court should be interpreted consistently with the obligations states have under this treaty regime," added Taylor.

She urged the ICJ judges "to ensure that its opinion preserves and promotes the centrality of this regime."

Campaigners were quick to lash out at the US statement before the court.

Vishal Prasad, Director of the Pacific Islands Students Fighting Climate Change, said: "Once again, we witness a disheartening attempt by the US to evade its responsibilities as one of the world's largest polluters."

Prasad said Washington had shown a "blatant disregard for the pressing urgency of the climate crisis."

"Instead, the US is content with its business-as-usual approach and has taken every possible measure to shirk its historical responsibility, disregard human rights, and reject climate justice."

The UN has asked the ICJ to develop a legal framework to flesh out states' responsibilities in tackling climate change, as well as the legal consequences for states that cause damage to the climate.

But the world's top two polluters have urged the court to stick to the current process, known as the UN Framework Convention on climate change (UNFCCC).

In its statement on Tuesday, Beijing's representative Ma Xinmin said: "China... hopes that the court will uphold the UN climate change negotiations mechanism as a primary channel for global climate governance."

The historic hearings at the ICJ will see more than 100 countries and organisations present their views on climate change -- the highest number ever.

The ICJ will likely take months if not years to deliver its opinion, which critics say would have limited impact given its non-binding nature.

Taylor also appeared to dismiss the idea that the ICJ should propose in its opinion that historic emitters be held responsible for past pollution.

"An advisory proceeding is not the means to litigate whether individual states or groups of states have violated obligations pertaining to climate change in the past or bear responsibility for reparations... nor would it be appropriate to do so," she said.