LONDON/NEW YORK Mon May 26, 2014 10:17am EDT

LONDON/NEW YORK (Reuters) – Pfizer said on Monday it had abandoned its current attempt to buy AstraZeneca for nearly 70 billion pounds ($118 billion) as a deadline approached without a last-minute change of heart by the British drugmaker.

"Following the AstraZeneca board's rejection of the proposal, Pfizer announces that it does not intend to make an offer for AstraZeneca," Pfizer said in a short news release.

Pfizer had until 5.00 pm (1200 ET) on May 26 to make a firm offer or walk away, under UK takeover rules. Its decision to quit the stage, at least for now, had been widely expected after AstraZeneca refused its final offer of 55 pounds a share.

The biggest U.S. drugmaker promised it would not go hostile, leaving the fate of what would have been the world's largest ever drugs merger in the hands of its target, whose board would have had to make a complete U-turn to get a deal done.

British rules now require an enforced cooling-off period. AstraZeneca could reach out to Pfizer after three months and Pfizer could take another run at its smaller British rival in six months time, whether it is invited back or not.

(Reporting by Ben Hirschler, editing by David Evans)