Labour has called on Theresa May to stand up to Donald Trump over his treatment of migrant children ahead of the US president's visit to the UK next month.
Shadow foreign secretary Emily Thornberry denounced a policy which has seen around 2,000 children divided from their families in six weeks on the southern US border as "abhorrent and repulsive".
Labour leader Jeremy Corbyn said it was "tragic and shocking" to see the children held in cages at migrant camps as their parents were taken off for prosecution.
Mr Trump is facing pressure from both sides of the political divide in Washington to end a "zero-tolerance" approach to illegal border crossings which requires adult migrants to be held in custody for prosecution, separated from their children.
Laura Bush, the wife of Republican former president George W Bush, has branded the policy "cruel and immoral", and Mr Trump's own wife Melania issued a statement to say that she "hates to see children separated from their families".
Ms Thornberry said: "This abhorrent and repulsive policy has no place in any civilised society, and for those of us who love the United States and its people, it is truly appalling to see these acts of wickedness carried out by their government, if not in their name.
"The truth is that every time you think Donald Trump cannot sink any lower, he finds new depths of depravity, and the fact that he actively revels in this policy makes you wonder if he has any shame left in his body, let alone a shred of decency or morality.
"It is repugnant to think that, in just three weeks' time, Theresa May's Government will roll out the red carpet for a man like that.
"What will it take before she starts standing up to this president on behalf of the British people, rather than meekly holding his hand and hoping he will eventually start to behave?"
In a tweet, Mr Corbyn said: "It's tragic and shocking to see innocent children caged like animals at US migrant camps and to hear their cries of anguish after being forcibly separated from their parents.
"It's immoral and goes against fundamental human rights we must always respect, no matter the situation."
Theresa May's official spokesman declined to comment on the US administration's approach when questioned at a regular media briefing in Westminster.
Instead, he stressed that the UK had no plans to institute a similar policy here.
"I would point you to the UK's own immigration policy," said the PM's spokesman. "It doesn't apply those measures and we don't intend to do so.
"The welfare and safeguarding of children is at the heart of our immigration policy. We don't separate child asylum seekers or refugees from their families.
"We believe that we have a humane system."