LONDON (AFP) - US drugs giant Pfizer on Sunday announced it had made a final improved bid for British competitor AstraZeneca, valuing the company at £69 billion (S$145.2 billion).

In a letter written from Pfizer Chairman and CEO Ian Read to AstraZeneca Chairman Leif Johansson, the US giant explained Pfizer and AstraZeneca shareholders would own "approximately 73 per cent and 27 per cent, respectively, of the combined company.

"The improved proposal values AstraZeneca today at approximately £69 billion," it added.

Read insisted that the deal "presents compelling strategic, operational and financial advantages that are in the best interests of all stakeholders.

"The improved proposal provides a highly attractive value creation opportunity for AstraZeneca shareholders through a substantial and immediate premium, a significant and increased cash component, and the longer term ability to participate in the success of the combined company," he added.

Pfizer's most recent offer of US$106 billion for the buyout was rejected by AstraZeneca. British regulators had set May 26 as the deadline for US firm to either raise its bid, launch a hostile takeover or abandon the effort.