IAN Blackford has called on Theresa May to cancel Donald Trump’s visit to Britain next month as he decried the US Government’s “vile” and “barbaric” treatment of child migrants, some of whom have been locked up in cages.

The SNP leader’s intervention came as there appeared to be a change of heart in the White House amid worldwide condemnation of the TV pictures showing child migrants being separated from their parents.

For weeks the US President refused to reverse his administration’s “zero tolerance” enforcement policy, which has led to the separation of more than 2,300 children from their parents at the border.

Earlier this week, Kirstjen Nielsen, America’s Homeland Security Secretary, insisted her country had “compassion” but stressed: “Parents who entered illegally are by definition criminals...By entering our country illegally often in dangerous circumstances, illegal immigrants have put their children at risk.”

But condemnation of the policy has been widespread; from world leaders and captains of industry to ordinary members of the public.

All four living former First Ladies – Rosalynn Carter, Hillary Clinton, Barbara Bush and Michelle Obama - denounced the US administration’s approach as “immoral” and “disgraceful”. Even the current incumbent, Melania Trump, appeared to agree, stressing how the US should "govern with heart".

With just five months to go before the midterm elections, Republicans are becoming increasingly concerned as opinion polls show a majority of Americans oppose the family separations.

After speaking to senators in the White House, Mr Trump announced he would be signing an executive order to reverse policy.

He told reporters: “We’re going to keep families together but we still have to maintain toughness or our country will be overrun by people, by crime, by all of the things that we don’t stand for and that we don’t want.”

At Westminster, Mrs May came under pressure at Prime Minister’s Questions to condemn Mr Trump’s separation policy. She said: "The pictures of children being held in what appear to be cages are deeply disturbing. This is wrong, this is not something that we agree with. This is not the United Kingdom's approach.”

But the PM stressed that the UK-US special relationship meant that she could fully air disagreements, which Britain had with American policy, with the President.

She was responding to Mr Blackford, who said her answer was "disappointing" and declared: “We should all be unreservedly condemning the actions of Donald Trump."

Later, asked if he was happy for the President’s July 13 visit to Britain to go ahead, the Highland MP replied: “On the basis of where we are now, it is right the Trump visit is called off.

“We should not be laying out the red carpet. If he does come, we would have to accept our responsibilities, whether it’s myself or the Government in Edinburgh, to meet him. But I don’t think it would be acceptable for the US President to visit at the current time.”

The SNP leader has written to Mrs May, highlighting the “horrific and distressing scenes of children being separated from their families in US detention centres” and “locked up like animals in cages”.

He calls on the PM to make “direct representations” to the President to urge him “to end this barbaric practice. Children cannot and should not be subjected to this treatment. It is inhumane”.

Mr Trump is due to arrive in the UK on Friday July 13. Woody Johnson, the US ambassador, made clear the President would meet the Queen during his visit.

He explained how “various scenarios” were being drawn up for Mr Trump’s itinerary but they all involved seeing Her Majesty.

Speculation is rife that the President will include in his trip a visit to Scotland to play a round of golf at one of his business empire’s courses.

Large protests are expected, which has led to suggestions Mr Trump will avoid London, visiting the PM at Chequers in Buckinghamshire and the Queen at Windsor Castle.