Jeremy Corbyn would effectively lower the UK's defences to its enemies around the world if the Labour leader gained power and ruled out ever using nuclear missiles, Michael Fallon has warned. The Conservative defence secretary argued it was vital for Britain's self-defence for a prime minister to be prepared to use the weapons of mass destruction.

"The Labour leader is effectively saying he would lower Britain's defences. Deterrents don't work if you're not prepared to use them. Having nuclear weapons and our enemies knowing that we're prepared to use them in the most extreme circumstances of self-defence is vital to keeping our country safe," Fallon argued.

The top Tory issued the warning after Corbyn revealed on 30 September that he would not use the Trident deterrent system even if a Labour government renewed the system. Corbyn told BBC Radio 4's Today programme: "I am opposed to the use of nuclear weapons. I am opposed to the holding of nuclear weapons. I want to see a nuclear-free world. I believe it is possible."

Corbyn, also the vice-chairman of the Campaign for Nuclear Disarmament (CND), has faced opposition from his own shadow cabinet over his anti-Trident position. He restated his stance over the controversial weapons during his keynote speech to Labour's annual conference in Brighton on 29 September.

"I've made my own position on one issue clear. And I believe I have a mandate from my election on it," he said. "I don't believe £100bn [$151bn] on a new generation of nuclear weapons taking up a quarter of our defence budget is the right way forward. I believe Britain should honour our obligations under the Non-Proliferation Treaty and lead in making progress on international nuclear disarmament.

"But in developing our policy through the review, we must make sure all the jobs and skills of everyone in every aspect of the defence industry are fully protected and fully utilised so that we gain from this, we don't lose from this. To me, that is very important."

However, shadow defence secretary Maria Eagle warned Corbyn's remarks "undermined to some degree" her review into the party's defence policy when she was questioned by the BBC. Elsewhere, shadow foreign secretary Hilary Benn has described Trident as the "cornerstone of security".

The row will likely play into the hands of the Conservatives, who have repeatedly attempted to paint Corbyn as a threat to "national and economic security", and the SNP, who are opposed to the renewal of the nuclear missile system.