He said the company would consider moving its US operations to India or China if the climate for operating in the sector deteriorates, according to a report in UK newspaper The Daily Telegraph.

The US is the world's largest market for pharmaceuticals, and the pharmaceutical industry is concerned that a flood of cheap parallel imports from Canada and other foreign countries could undermine its profitability and the ability to invest in the R&D needed to bring new medicines to market.

Speaking at the BioVision World Life Sciences Forum Sir Tom said that the US is running the risk of losing its lead in pharmaceutical innovation if it embraces parallel imports.

AstraZeneca has already shifted some of its operations to Asia to take advantage of a combination of cheaper labour costs and a highly-skilled workforce. The company has opened an R&D centre in Bangalore, India, and is one of the largest foreign investor in the pharmaceutical sector in China, where it operates a manufacturing facility.

Sir Tom's comments come at a time when the USA is seeing bipartisan efforts by Senators to introduce a bill that would legalise access to reimported medicines, which at the moment is illegal under US law. Some states, notably Illinois, Vermont, Wisconsin and Minnesota, have already set up cross-border measures to get access to lower-priced Canadian medicines.