LONDON  —  Radiohead frontman Thom Yorke says he turned down the chance to discuss climate change with Tony Blair because the British prime minister has "no environmental credentials."

The charity Friends of the Earth, for which the singer is an ambassador, asked him to meet Blair.

But Yorke said Blair had no record of championing the environment and added that dealing with the governing Labour Party's "spin doctors" made him feel ill.

"I got so stressed out and so freaked out about it. Initially when it came up I tried to be pragmatic," Yorke told New Music Express magazine in an issue out Tuesday. "But Blair has no environmental credentials as far as I'm concerned."

"It was like talking to Blair's spin doctors. It was all getting weird. It was just obvious there was no point in meeting him anyway, and I didn't want to," he said.

Yorke says the experience has soured him on political activism.

"I came out of that whole period just thinking, I don't want to get involved directly, it's poison. I'll just shout my mouth off from the sidelines."

Yorke is backing Friends of the Earth's Big Ask campaign, which is calling for international cuts in greenhouse gas emissions.

Radiohead will play a benefit concert for the campaign at London's Koko Club on May 1. The band recently announced a club tour in England.

They have been working on new material for the follow up to their politically-themed 2003 disc, "Hail to the Thief."