US drugs giant Pfizer on Sunday announced it had made a final improved bid for British competitor AstraZeneca, valuing the company at £69 billion ($117 billion). The offer of £55 a share is 15 percent higher than its last bid, made on May 2, and also is the fourth and final approach, Pfizer said, but added it did not expect the AstraZeneca board to accept the new deal. The US company explained it would not make a hostile offer to AstraZeneca shareholders, but hoped they would put pressure on the company's board to engage with the offer. Under the new offer, shareholders from the US group would own approximately 73 percent of the new firm, while the British group's shareholders would hold 27 percent. "The improved proposal values AstraZeneca today at approximately £69 billion," Pfizer Chairman and CEO Ian Read wrote in a letter dated May 16 to AstraZeneca Chairman Leif Johansson. In a statement outlining the offer and latest discussions with the British group, Read said: "We have tried repeatedly to engage in a constructive process with AstraZeneca to explore a combination of our two companies. "Following a conversation with AstraZeneca earlier today, we do not believe that the AstraZeneca board is currently prepared to recommend a deal at a reasonable price. "We remain ready to engage in a meaningful dialogue but time for constructive engagement is running out." Read insisted that the deal "presents compelling strategic, operational and financial advantages that are in the best interests of all stakeholders." Pfizer's most recent offer of $106 billion for the buyout was rejected by AstraZeneca. British regulators had set May 26 as the deadline for Pfizer to either raise its bid, launch a hostile takeover or abandon the effort. -- Jobs to go -- Politicians and unions have expressed concern that a tie-up would lead to job cuts and damage Britain's position as a research and development hub. British Prime Minister David Cameron recently called on Pfizer to give more assurances that its takeover bid is in Britain's national interest. He dismissed suggestions from the leader of the main opposition Labour Party, Ed Miliband, that he was "cheerleading" for the deal by instructing cabinet ministers to discuss the situation with both companies. In the United States, meanwhile, two US governors have pressed Pfizer about the impact on jobs in their states, while a US senator has called for an overhaul of the tax code to discourage deals like the one Pfizer is pursuing. AstraZeneca employs 6,700 people in Britain and the head of Pfizer, Ian Read, conceded that jobs could be lost if the takeover succeeds. Pressed repeatedly last week by a British parliamentary committee on what savings Viagra maker Pfizer was planning to make in the event of a tie-up, Read admitted "there will be some job cuts somewhere". "I'm not sitting here saying that we can become more efficient without some reduction in jobs. We'll be more efficient by some reduction in jobs. What I can't tell you is how much or how many or where," he told the committee. His counterpart at AstraZeneca, Pascal Soriot, has meanwhile warned that a Pfizer takeover could delay the production of life-saving drugs. Pfizer wants to create a new pharmaceuticals giant that will be domiciled for tax purposes in Britain.