LABOUR members issued clear instructions to their representatives in Parliament yesterday not to sanction air strikes on Syria without UN authorisation.

Shadow chancellor John McDonnell called for a free vote if PM David Cameron stages a second vote on bombing Syria.

But conference backed a Unite motion demanding that MPs oppose intervention without stringent safeguards.

Proposing the motion, Unite delegate Ivan Monckton said: “It’s time to get behind diplomacy and end the Syrian civil war.

“Labour must once more stand up for peace and against another Cameron war. Now is the time for peacemongers not warmongers.”

The resolution will not be binding on MPs.

Meanwhile Mr Corbyn created a stir after stating that he would never push the nuclear button if he becomes prime minister.

Unleashing nuclear weapons would be “immoral,” Labour’s leader said as the shafted debate over Trident renewal continued to a blot on an otherwise upbeat conference.

Asked whether he would launch a nuclear strike if he was in No 10, Mr Corbyn answered: “Would anybody press the nuclear button?”

“They’re the ultimate weapon of mass destruction that can only kill millions of civilians if ever used,” he added.

“I am totally and morally opposed to nuclear weapons. I do not see them as a defence.”

Shadow defence secretary Maria Eagle claimed his comments “undermined to some degree” the review of the party’s policy on nuclear weapons which she has launched.

“I don’t think that a potential prime minister answering a question like that, in the way in which he did, is helpful,” she said.

Trident workers’ union GMB general secretary Paul Kenny said that if Mr Corbyn became PM he would “have a choice to make in terms of whether he followed the defence policy of the country, or felt that he should resign.”

Seeking to prevent a war of words, Mr Corbyn pointed out the vote over Trident renewal was not for another year and pledged to “live with” the party’s decision.

But he branded nuclear weapons a cold war relic that “didn’t do the US much good” on September 11 2001.