LONDON (Reuters) - Prime Minister Rishi Sunak has set Britain back on tackling climate change and must do more on heating and industrial emissions to stop slipping behind other nations, the head of the government's advisory body has said.

Chris Stark, who will step down as chief executive of the independent Climate Change Committee next week, told the BBC broadcaster that UK climate policy had become less ambitious.

"That is extremely hard to recover," Stark said, according to excerpts from the interview due to air on Sunday.

"I think it's set us back."

Under pressure to address cost-of-living concerns and trailing the opposition Labour Party before an election later this year, Sunak has outraged environmental campaigners by watering down some measures to reach net zero emissions.

He says delaying targets for changing cars and domestic heating are pragmatic moves needed to maintain the consent of the British people, with the country's commitment to reach net zero by 2050 still intact.

Stark, who has run the committee since April 2018 but will now join consultancy the Carbon Trust as chief executive later this year, said Britain needed to do more work on how homes were heated and industrial emissions managed, as well as in the farming and transport systems.

"I definitely feel we're at risk," he said.

Asked about Stark's comments, a government spokesperson said Britain was the first major economy to halve greenhouse gas emissions since 1990 and had set into law one of the most ambitious 2035 climate change targets.

"But we need to reach our net zero goals in a sustainable way so we have taken action to protect our energy security, ease the burdens on hard-working people and provide transparency about the choices involved so that we bring people with us in meeting our climate targets," the spokesperson added.

(Reporting by Elizabeth Piper; Editing by Andrew Cawthorne)

By Elizabeth Piper