Gilead Sciences is to create new UK commercial headquarters in London and expand its existing operations in the country.

The US biotech major is setting up home in Holborn and expanding its international operations in Uxbridge and UK R&D headquarters in Cambridge. The moves represent an increased investment of $19.6 million, doubling Gilead’s UK workforce to 600 by the end of the year - 400 will be based in London.

Boston-based Gilead's investment was announced by Mayor of London Boris Johnson on US trade mission to drum up new business for the capital. The announcement comes less than a year since he launched MedCity, which aims to help the life sciences industry in London and the greater south east of England.

Mayor Johnson also announced that another Boston-based company Mobiquity, which specialises in mobile health, is investing £13 million over the next two years in a new London base. He said that Gilead and Mobiquity's moves to London “further underline the growing importance of the life sciences industry in the UK as we look to ensure that this crucial sector becomes a key contributor to the capital's growth and health”.

In November, Merck & Co announced a £42 million investment to create a new London licensing hub, expand research in Hertfordshire and fund clinical research in oncology and dementia. Pfizer is setting up a new gene therapy unit in the capital focused on rare diseases.