British Prime Minister Boris Johnson is putting the National Health Service (NHS) off limits in any trade deal with the United States, Trend reports citing Reuters.

"The Prime Minister has asked me to underline that measures affecting the NHS, including service provision and drug pricing, cannot under any circumstances form part of an agreement with the United States," a letter from Johnson's senior staff to Trade Secretary Liz Truss's office said, according to the report.

The letter continued that there should be no internal discussion of the issues within the government. Johnson fears the Labour Party would use any suggestion that NHS access is up for grabs to its electoral advantage, the article said.

U.S President Donald Trump had said in June that Britain’s public health service should be on the table in talks about a trade deal between the two countries after Brexit but later backtracked on his comments.