U.S. drugmaker Pfizer has dismissed criticism that its planned takeover of rival AstraZeneca would damage Britain's science base, saying strong UK research was a key reason for the deal.

Given its record of big job cuts after past acquisitions, the U.S. group has come under fire in the UK, the U.S. and Sweden as it weighs its next move to buy AstraZeneca.

Chief Executive Ian Read, who is due to appear before two panels of British lawmakers on May 13 and 14, said in a video that the $106 billion deal was a "win-win" for shareholders and society.

The suggested deal would be the largest foreign takeover of a UK company and has provoked a political storm in Britain, with the government seeking binding commitments to protect skilled jobs and scientific research.

Two U.S. state governors with large AstraZeneca workforces have also joined the fray, while the prime minister of Sweden - where AstraZeneca has half its roots - has expressed concerns.

Read rejected suggestions from AstraZeneca CEO Pascal Soriot that a merger would be disruptive and could damage the development of a series of experimental drugs currently in clinical testing.

"The integration of the two scientific bases, in my opinion, will be very easy," the Pfizer leader said, arguing that the company's R&D system gives substantial autonomy to scientific leaders within specific diseases areas.

AstraZeneca has rejected Pfizer's approaches to now, arguing that its cash-and-shares offer of £50 per share significantly undervalues Britain's second-biggest pharmaceuticals company, which has a bright future as an independent business.

The Pfizer CEO did not deny that the proposed deal would lead to some job losses and that a plan to redomicile the enlarged company in Britain would cut its taxes, but he said such things were necessary to improve efficiency.

"Governments are all around the world pressurising the industry to produce products of higher value and with more productivity, at lower cost," he said. "So one way of doing that is to consolidate and is to take out overlapping functions."

Under British takeover rules, Pfizer has until May 26 to make a firm bid for AstraZeneca or walk away.