LONDON, Dec 1 (Reuters) - Britain and the United States are poised to agree to zero tariffs on pharmaceutical products, with an announcement due at the White House on Monday, according to two sources familiar with the matter.

The White House and the British government did not immediately respond to requests for comment.

British Science Minister Patrick Vallance told lawmakers in October that "some degree of price increase is inevitable" for new, innovative medicines under the talks, though existing drugs and generics may not see the same rises.

U.S. President Donald Trump has pressed Europe to pay more for American medicines, and major pharmaceutical firms have delayed investment in Britain, citing a tough operating environment.

The two countries agreed in May to seek "significantly preferential treatment outcomes on pharmaceuticals," with a commitment that Britain tries to improve the environment for pharma firms operating in the country.