The British pharmaceutical company, GlaxoSmithKline plc, still sees the UK as “an attractive location” regardless of Brexit.
Chief executive Andrew Witty backed the Remain campaign, said the decision for investment was due to the UK’s skilled workforce, and modest tax system.
Most of the products produced at the expanded sites will be exported. The new investment is also expected to create new jobs.
Mr Witty said: “It is testament to our skilled UK workforce and the country’s leading position in life sciences that we are making these investments in advanced manufacturing here.”
GSK confirmed that the planned investment will be spread across three of its UK manufacturing sites: Ware in Hertfordshire, Barnard Castle in County Durham, and Montrose in Angus.
The firm currently employs over 15,000 people in the UK, which sees 6,000 employed in manufacturing.
Initially, there were concerns after the outcome of the EU referendum that pharmaceutical firms, GSK and AstraZeneca could move their headquarters.
After GSK’s announcement, Greg Clark the Business and Energy Secretary, said: “An investment of this scale is a clear vote of confidence in Britain and underlines our position as a global business leader.
“GSK’s recognition of our skilled workforce, world leading scientific capabilities and competitive tax environment is further proof that there really is no place better in Europe to grow a business.”