Theresa May said that she 'absolutely condemns' the use of torture - only hours after President Trump declared that water boarding and other harsh interrogation techniques 'work'.
When questioned about their differing styles before landing in Philadelphia, Mrs May told reporters: 'Haven't you ever noticed that sometimes opposites attract?'
The split threatens to create major tensions in the relationship between British spies and their US counterparts, which is currently rated the best in the world.
The UK's strict rules state that officials will not share intelligence with countries if it involves a serious risk of a detainee being tortured, or that is how the information was obtained.
In comments that triggered anger from human rights groups, President Trump yesterday threatened to revive some of the techniques used during a George W Bush's ill-fated 'war on terror'.
He said: 'I have spoken with people at the highest level of intelligence and I asked them the question 'Does it work? Does torture work?' and the answer was 'Yes, absolutely'.
Mrs May has been careful to find common ground with Mr Trump on issues such as trade and the Middle East.
But, speaking to reporters on a flight to the US to meet the President, she said Britain would be sticking to its guns on torture - and was prepared to deliver this message direct to the Trump administration.
The PM said: 'The UK Government's position on torture has not changed. We condemn torture and my view on that will not change whether I am talking to you or talking to the President.
'Our guidance is very clear about the position that the UK takes and our position has not changed.
'We have a very clear view in the U.K. That we absolutely condemn the use of torture and that has not changed and will not change.'
The British guidelines on the use of torture were laid down by David Cameron in 2010 amid accusations the Tony Blair government had turned a blind eye to the ill treatment of detainees during his cosy relationship with President Bush.
They state that: 'When we work with countries whose practice raises questions about their compliance with international legal obligations, we ensure that our co-operation accords with our own international and domestic obligations. We take great care to assess whether there is a risk that a detainee will be subjected to mistreatment and consider whether it is possible to mitigate any such risk.
'In circumstances where, despite efforts to mitigate the risk, a serious risk of torture at the hands of a third party remains, our presumption would be that we will not proceed. In the case of cruel, inhuman or degrading treatment or punishment, this will cover a wide spectrum of conduct and different considerations and legal principles may apply depending on the circumstances and facts of each case. '
Police and prosecutors in Britain have made it clear they will pursue cases where there is evidence of British complicity in torture.
MI5 and MI6 both faced probes into the alleged conduct of unnamed officers in relation to the war on terror.
Source: Daily Mail