PARIS: An `explosion` of multibillion-dollar claims by fossil fuel and extractive firms through shadowy investment tribunals is blocking action on climate and nature, the UN Special Rapporteur for Human Rights and Environment has warned, with developing nations increasingly targeted.

After countries agreed this week at UN climate talks on a `transitioning away from fossil fuels`, governments are likely to come under heightened pressure to boost regulation and reject further expansion of oil, gas and coal projects.

But that could leave them open to litigation under a secretive arbitration process called investor-state dispute settlement (ISDS), according to UN rights expert David Boyd,who has called it a `major obstacle` to environmental action.

`When governments bring in these stronger laws and policies, they`re ending up paying millions and sometimes billions of dollars in compensation,` Boyd told AFP.

Denmark, France and New Zealand have all backed off from stronger regulation on fossil fuel exploration because of ISDS fears, he said.

In a report called `Paying Polluters`, presented to the UN General Assembly earlier this year, Boyd warned that the number of claims and the size of the payouts were soaring.

`The explosion of ISDS claims in recentyears,and the threat ofsuch claims, is led by fossil fuel, miningand other extractive industry corporations,` Boyd said in his report.

ISDS cases targeting actions to protect the environment rose from 12 initiated before 2000, to 37 from 2000 to 2010, and 126 between 2011 and 2021, it said, adding fossil fuel and mining industries have won over $100 billion in awards. That could rise substantially, as `sunset clauses` mean even if a state pulls out of a treaty it could still face litigation for some two decades.

ISDS mechanisms built into thousands of international treaties have roots in the global reconfiguration after World War Two, as investors based often in former colonial powers sought to protect assets in newly-independent countries.-Reuters