Sir Keir Starmer has lashed out at the SNP’s renewed calls for Britain to scrap its independent nuclear deterrent amid the Ukraine crisis.

The Prime Minister said John Swinney’s reaffirment last week that his party was opposed to Trident, which is based on the Clyde, was “completely wrong-headed”.

Responding to Stephen Flynn, the SNP’s Westminster leader, in the Commons, Sir Keir said now was not the time to “reduce our security or defence”.

He urged the SNP to reconsider its long-standing opposition to nuclear weapons, with France and Britain’s nuclear arsenals being viewed as increasingly vital for Europe’s security in light of Donald Trump’s threat to withdraw military support.

But Mr Swinney, the First Minister, insisted last week that Trident was “providing no tangible or realistic benefit to the military challenges that we face at this moment”.

He argued that the nuclear deterrent should be scrapped and the savings spent on conventional weapons and foreign aid.

Mr Flynn had attacked Sir Keir’s “weak” response to Mr Trump and Volodymyr Zelensky’s spectacular falling-out in the White House on Friday.

However, this prompted a backlash against Mr Flynn and the Aberdeen South MP used his question in the Commons to perform an about-turn, praising Sir Keir’s leadership during the crisis.