Labour leader Jeremy Corbyn has warned Theresa May not to offer the NHS “up for sacrifice” when she meets US President Donald Trump.
Mr Corbyn said he would not allow the UK “to be sold off on the cheap”.
Mrs May said she was not afraid to speak frankly to President Trump, and that Mr Corbyn would never enjoy a “special relationship” with the US.
She faced several questions about Friday’s visit to the White House during PMQs in the Commons.
Mr Trump has promised a new UK-US trade deal will be negotiated “quickly”.
But Mr Corbyn raised concerns Mrs May would “offer up for sacrifice” public services and the NHS during their talks.
He accused the PM of “threatening” the EU with turning the UK into a “bargain basement economy” while offering President Trump a “blank cheque”.
“I am pleased I am able to meet President Trump so early in his administration,” the PM said.
“I am not afraid to speak frankly to a president of the United States of America – I am able to do that because of that special relationship – a relationship he would never have with the United States.”
Mr Corbyn’s predecessor as Labour leader, Ed Miliband, told Mrs May she had a “huge responsibility” with her meeting with President Trump, urging her to persuade the US president not to abandon the Paris climate change agreement and to persuade him that climate change was not a “hoax invented by the Chinese”.
The PM said the government wanted to the see the Paris agreement “put into practice”.
President Trump’s previous comments on the use of torture were raised by Conservative MP Andrew Tyrie.
During the presidential election campaign, Mr Trump said that “torture works” and promised to bring back “a lot worse than waterboarding”.
Mr Tyrie asked Mrs May to confirm that the UK would not facilitate torture under any circumstances.
The PM replied: “We have a very clear position on torture, we do not sanction torture, we do not get involved with that and that will be our position.”