PHARMACEUTICAL giant GlaxoSmithKline is investing £110 million in its plant at Montrose, the biggest single slice of a £275m capital spending package across three UK manufacturing sites.

In a major boost for the 450 staff currently employed at GSK's research and development hub in Montrose, the company confirmed it was creating a state-of-the-art scientific facility in the Angus town.

The company's research in Montrose is focused on the manufacture of active ingredients for respiratory and HIV medicines and vaccine products.

An additional £92m investment will fund the construction of an aseptic sterile facility in County Durham to support the manufacture of new and existing biopharmaceutical products, with £74m to help boost production of GSK's new Ellipta respiratory inhaler at its site in Ware, Hertfordshire.

GSK, brushing off Brexit jitters, said it still considered the UK to be an "attractive location" for investment despite the vote to leave the EU, adding that the cash injection would bring "new employment opportunities".

Chief executive Sir Andrew Witty - who has backed the Remain campaign - said that the UK's "competitive corporate tax system" and skilled workforce helped the pharmaceutical giant come to its decision.

He added: "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."

UK Government Minister Andrew Dunlop said the investment was "a real testament to the hard work and skills of the workforce in Montrose".

He added: "Above all, it is a clear vote of confidence in the country’s economy, and shows that Scotland and the UK are very much open for business."

The company's latest investment in Scotland comes just months after it announced plans in February to create an extra 55 jobs through a £70m extension of its antibiotics plant at Irvine in North Ayrshire, which has an existing staff of 399.

Chief executive, Sir Andrew, said GSK had opposed Brexit because of the "regulatory uncertainty" it would create for the sector, but said this concern "was not sufficient to get in the way of the decision to invest".

Speaking to BBC Radio 4 yesterday, Sir Andrew said: "Over the medium run - assuming the outcome on the regulatory regime change is not unnecessarily disruptive - I would expect our overall footprint to broadly continue as it is, with the very substantial proportion in the UK."

However, he cautioned the Government against rushing into negotiations by swiftly triggering Article 50 of the Lisbon Treaty.

"I don't think it's important when we start the process," said Sir Andrew. "I think it's important when we finish and the quality of what comes out of the negotiation. If I had any advice to the Government, it would be don't rush to start the race and don't put unnecessary time pressure on yourselves in the negotiation."

The news of its £275m investment came as GSK reported that its second-quarter operating profit rose 15 per cent to £1.83 billion as sales of new products more than doubled.

Group sales increased four per cent to £6.53 billion with growth across pharmaceuticals, vaccines and in consumer healthcare.

Sales were driven by HIV drugs Tivicay and Triumeq, respiratory drugs such as Relvar/Breo and meningitis vaccines including Bexsero.

The company said the growth offset the decline in sales of blockbuster drugs like Advair.

GSK shares finished 29.5p up - or 1.8 per cent higher - at 1696.5p.