GlaskoSmithKline say investment should create 'several hundred jobs'
£92million is being invested at the Barnard Castle site, where over 1,000 people are already employed.
GlaxoSmithKline has announced that it is pumping £275 million into its three UK manufacturing sites, including the site in Barnard Castle.
Bosses there say "new employment opportunities'' are expected to be created as a result.
Barnard Castle in County Durham is one of GSK’s biggest secondary manufacturing sites, employing 1,100 people.
The site supplies nearly half a million packs of products per day to 140 global markets.
The investment of £92 million will fund the construction of an aseptic sterile facility supporting the manufacture of existing and new biopharmaceutical assets in our pipeline.
Site director Alastair Leighton said: "With a construction and engineering project of this scale, there will be several hundred jobs here for the next 3-5 years just in terms of building.
"Then looking to commercialise and operationalising that faclity.
"Despite Brexit, we still have the skilled workforce, we still have the strong legacy in compliently manufacturing these types of products and making sure patients around the world can get access to these innovative medicines.
"This a strong signal that GSK are here to stay."
Chief executive Andrew Witty said that the UK's competitive corporate tax system'' and skilled workforce helped the pharmaceutical giant come to its decision.
Mr Witty, who backed the Remain campaign during the referendum, said: Today's announcement reflects further investment to support our pharmaceutical pipeline and meet growing demand for our innovative portfolio of newly launched products.
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. From their manufacture in the UK, many of these medicines will be sent to patients around the world.''
Business and Energy Secretary Greg Clark 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.''