Prime Minister Rishi Sunak has been accused of “a failure of leadership” for not attending the COP27 climate summit next month.
Opposition parties and environmental groups said the decision showed the government was not taking the climate crisis seriously enough.
Downing Street said the PM had “other pressing domestic commitments including preparations for the autumn Budget”.
Mr Sunak’s predecessor Liz Truss had been due to attend the conference.
Environment Secretary Therese Coffey told the BBC she was planning to to attend along with the outgoing Alok Sharma, who was president of last year’s COP in the UK.
Defending Mr Sunak’s decision, Ms Coffey said the “big political moments” tended to happen at the conference every five years – such as last year’s summit in Glasgow – and that this year’s conference would be more about implementation.
She insisted that “protecting the planet is absolutely a priority for the government”.
“We remain committed to net zero and to leading international and domestic action to tackle climate change. The UK is forging ahead of many other countries on net zero,” she added.