BEIJING, April 8 -- Yahoo! Inc, responding to Microsoft Corp's weekend threat of a proxy fight that could result in a lower takeover price, said the current 44.6 billion U.S. dollars offer must be raised before any merger can take place. "We will not allow you or anyone else to acquire the company for anything less than its full value," Yahoo said on Monday in a letter to Microsoft Chief Executive Officer Steve Ballmer. Last Saturday, Ballmer gave Yahoo three weeks to reach a deal or face a proxy battle.

Yahoo, owner of the most visited US website, said it isn't against a combination with Microsoft at a superior price and rejected Ballmer's charge that its business has deteriorated. Yahoo called Microsoft's threat "counterproductive" and is still evaluating alternatives to the bid, which was 62 percent higher than its stock price at the time of the offer. "We are open to all alternatives that maximize stockholder value," CEO Jerry Yang and Chairman Roy Bostock wrote. "This includes a transaction with Microsoft if it represents a price that fully recognizes the value of Yahoo on a standalone basis." Yahoo, based in Sunnyvale, California, fell 66 cents to 27.70 dollars in early trading after closing at 28.36 dollars on the NASDAQ Stock Market on Friday. Microsoft, the world's biggest software company, made the 31 dollars-a-share offer on Jan 31. Its shares have fallen since the bid, closing last week at 29.16 dollars, valuing the half-cash, half- stock bid at about 29.36 dollars a share. Microsoft spokeswoman Dawn Beauparlant didn't immediately return a telephone call seeking comment. Cat and mouse Ballmer's ultimatum shows Microsoft is in a hurry to secure Yahoo to take on Google Inc, which dominates in Internet search, said analysts including Canaccord Adams' Colin Gillis. "Microsoft doesn't want to spend a year negotiating, playing cat and mouse with the Yahoo board and another year to close this transaction to get all the regulatory approvals," said New York-based Gillis, who advises investors to buy Yahoo stock. "The Yahoo board should come to the tab