Speculation is mounting that Pfizer may make a fresh offer to buy AstraZeneca, three months after the Amercian firm's £69billion bid collapsed.

Under takeover rules Pfizer could lodge a private bid - given three months has now passed - while AstraZeneca could also invite the company back into negotiations.

It comes after AstraZeneca shares rose more than 7 per cent last week.

A number of AstraZeneca shareholders were reportedly frustrated that chief executive Pascal Soriot didn't negotiate more with Pfizer initially.

In terms of making a public bid - Pfizer wouldn't be able to do that until around November, which marks six months after AstraZeneca rejected its last offer.

AstraZeneca is moving to Cambridge from Alderley Park in Cheshire.

The firm also employs 2,000 people at a factory in Macclesfield.