Pfizer has sweetened its bid to acquire AstraZeneca to £55 from £50 per share, saying it is a final offer.

The new offer values the Anglo-Swedish drugmaker at £69.3 billion and increases the cash element to 45% from 32%, with the rest payable in Pfizer shares. The US major stressed that the "improved proposal is final and cannot be increased" and it will not make a hostile offer directly to shareholders. The company "will only proceed with an offer with the recommendation of the AstraZeneca board".

The figure off £55 has been mentioned in many circles as the level whereby a deal could move forward. Pfizer had offered £3.50 more per share on May 16 but said that during discussions earlier today (Sunday), "AstraZeneca made clear that it is not currently prepared to accept a price close to Pfizer’s £53.50 proposal".

Chief executive Ian Read said "we have tried repeatedly to engage in a constructive process[but] we do not believe that the AstraZeneca board is currently prepared to recommend a deal at a reasonable price". He added that "we remain ready to engage in a meaningful dialogue but time for constructive engagement is running out", claiming that "other issues that have been raised by AstraZeneca do not represent material difficulties".

The ball is now firmly back in the court of AstraZeneca which has repeatedly expressed its desire to remain independent. Public sentiment, in the UK at least, has been against the deal but whether shareholders are tempted by the £55 figure is likely to be the deciding factor.