Hugh Montefiore was Bishop of Birmingham from 1978-87

Friends of the Earth (FoE) says Rt Rev Hugh Montefiore's support for nuclear energy to tackle global warming is not compatible with the charity's aims.

The bishop, who believes the uptake of renewable energy sources is taking too long, says he is "sad" to be resigning.

He added it was "vital" nuclear power became more acceptable in Britain.

"I'm not objecting to having to resign, although I'm very sad about it," the bishop told BBC Radio 4's Today programme.

If you have two people from the organisation saying different things, they're not going to have much impact Tony Juniper FoE director

"There are organisations which stage public debates, but this is a campaigning organisation so I suppose they feel they can't do this."

The bishop, who converted to Christianity from Judaism as a schoolboy, added: "I see very little happening in terms of the reduction of CO2s.

"Exciting things are happening in terms of renewables, but they're miles away from being commercially viable.

"It's an enormous break to have to cut by 60% by 2050 to make the planet decent. And I just cannot see this happening with renewables."

FoE director Tony Juniper said the group could no longer work with Rt Rev Montefiore, who is retired but is still an honorary bishop in the diocese of Southwark.

"We offered to do a review of our policies on climate change to check their adequacy and Hugh chose instead, before we finished that review, to put his views into the public domain. That's his choice.

"The organisation is very happy to have internal debates about policies, but in practical terms, if you have two people from the organisation saying different things, they're not going to have much impact.