ALOK Sharma, the Cabinet minister who led last year’s COP25 climate summit has said he will resign if the new prime minister is not fully committed to the net zero agenda.

Cop26 president Alok Sharma said that while it was “absolutely a leadership issue”, some of the remaining candidates in the Tory leadership race had been only “lukewarm”.

In an interview with The Observer, he urged them to “proactively” set out their support for the net zero agenda and “green” growth.

“Anyone aspiring to lead our country needs to demonstrate that they take this issue incredibly seriously, that they’re willing to continue to lead and take up the mantle that Boris Johnson started off,” he said.

Asked if he could resign if candidates were weak on net zero, Mr Sharma said: “Let’s see, shall we? I think we need to see where the candidates are. And we need to see who actually ends up in No 10.

“I hope every candidate realises why this is so important for voters generally and why it’s important for Conservative supporters. And I hope that we will see, particularly with the final two, a very clear statement that this is an agenda that they do support.”

Pressed a second time, he added: “I don’t rule anything out and I don’t rule anything in.”

Of the five remaining candidates in the contest, only Kemi Badenoch has said she does not support the UK target of getting to net zero emissions by 2050, describing it as “unilateral economic disarmament”.

The others have indicated varying degrees of enthusiasm for the policy, which is unpopular with some sections of the party amid concerns about the impact on the economy.

Iain Duncan Smith, who is backing Foreign Secretary Liz Truss, said the priority for any new leader needed to be the cost of living crisis.