NO 10 has rejected Theresa May’s stern rebuke of Boris Johnson after she accused him of abandoning Britain’s position of “global moral leadership”.

The former Prime Minister warned Mr Johnson’s threat to override Britain’s treaty obligations in the Brexit divorce settlement risked signalling a “retreat” from the UK’s standing in the world.

However, Downing St said Britain would “continue to be a leading voice on the international stage” under Mr Johnson’s leadership.

Asked about his predecessor’s remarks, the PM’s spokesman said: “I would reject that characterisation. The UK is and will continue to be an outward-looking nation and will continue to be a leading voice on the international stage.”

In an article for the Daily Mail to mark the inauguration of Joe Biden as the US President, Mrs May said the new arrival at the White House represented a “golden opportunity” for Britain with the return of a more normal style of presidency.

But she said that, while the UK was well placed to play a decisive role in shaping a more co-operative world, this prospect had not been helped by Mr Johnson’s actions.

She again strongly criticised his threat – later withdrawn – to override elements relating to Northern Ireland in the Brexit Withdrawal Agreement and his decision to drop the commitment to spend 0.7% of national income on international aid.

“To lead we must live up to our values,” declared Mrs May. “Threatening to break international law by going back on a treaty we had just signed and abandoning our position of global moral leadership as the only major economy to meet both the 2% defence spending target and the 0.7% international aid target were not actions which, in my view, raised our credibility in the eyes of the world.

“Other countries listen to what we say not simply because of who we are, but because of what we do. The world does not owe us a prominent place on its stage.

“Whatever the rhetoric we deploy, it is our actions which count. So, we should do nothing which signals a retreat from our global commitments.”

During PMQs, Ian Blackford for the SNP pressed Mr Johnson over Mrs May’s remarks, noting how he had “cosied up to Donald Trump and his callous world view”.

He told MPs: “This morning the former PM, the member for Maidenhead[Mrs May] accused the current PM of abandoning moral responsibility on the world stage by slashing international aid.

“So, if today’s to be a new chapter, if today is a new start, will the PM begin by reversing his cruel policy of cutting international aid for the world’s poorest?”

Mr Johnson replied by stressing how very important it was for the PM of the UK to have the best possible relationship with the President of the US.

“That’s part of the job description,” he declared, saying: “As all sensible members opposite would acknowledge, and when it comes to global leadership on the world stage, this country is embarking on a quite phenomenal year…with the G7, with COP26 and we’ve already led the world with the Gavi summit for global vaccination raising 8.8 billion dollars.

“It was the UK, the first major country in the world to set a target of net zero carbon emissions by 2050…We’ll work with President Biden to secure the transatlantic alliance and Nato, which, of course, the SNP would unbundle, well, I think they would,” he added.