Pharmaceutical giant AstraZeneca is to buy US drug developer Alexion in a deal worth almost £30 billion.

Cambridge-based AstraZeneca, which is developing a Covid-19 vaccine, said on Saturday it is using a combination of cash and shares for the acquisition of Boston-based Alexion Pharmaceuticals.

The boards of both companies have unanimously approved the transaction, but it still needs regulatory and shareholder approval.

The deal is expected to close in the third quarter of 2021.

AstraZeneca chief executive Pascal Soriot said: “This acquisition allows us to enhance our presence in immunology.”

The company and Oxford University have jointly developed a coronavirus vaccine that British and Canadian regulators are assessing.