Britain’s biggest drugmaker AstraZeneca has said it will invest £300m in the UK in a surprise U-turn after pausing large-scale projects last year.

The drugmaker had pulled back projects in Britain after becoming disillusioned with the business environment, including the availability of new medicines on the NHS and drug pricing.

On Wednesday, it said it would invest in two existing sites at Cambridge and Macclesfield.

Keir Starmer announced the investment in the House of Commons, saying the move would protect jobs.

AstraZeneca will complete the construction of the Rosalind Franklin building on its Cambridge campus, where it has its headquarters. It will also build a “lab of the future” that will use digital and data tools to advance drug development at its Macclesfield site, Soriot said.

Last September, Astra paused a £200m investment in Cambridge, which followed the scrapping in January of plans to invest £450m in its vaccine manufacturing facility at Speke, Merseyside, citing a cut in government support, after months of negotiations.

Starmer said: “Today I can announce a significant new investment, by AstraZeneca, investing £300m in UK life sciences, made possible by the pharmaceutical arrangement we have struck with the United States, to future-proof thousands of jobs in Macclesfield and in Cambridge.

“That is a major vote of confidence in the UK, and Labour’s plans to strengthen our economy.”

Pascal Soriot, the company’s chief executive, thanked the government “for their effort to improve access for patients, including four new [drug] approvals since the beginning of the year, and we look forward to further enhancing the access and the reimbursement environment and build a strong life sciences sector”.

The move came as AstraZeneca and GSK both reported strong sales of cancer drugs, despite GSK taking a hit in the US potentially linked to “scepticism” over vaccines from Donald Trump’s administration.

AstraZeneca posted an 8% increase in revenues to $15.3bn in the three months to March, including 16% growth in oncology and a 15% rise in rare disease treatments.

GSK reported a 5% rise in sales to £7.6bn, with 28% growth in cancer drug sales, such as Jemperli for womb cancer. Vaccine revenues were up by 4% with the shingles jab Shingrix notching up £1bn in sales for the first time.