"There is no way Alan Shearer is going anywhere," the Rovers owner said from his Jersey home before instructing the club's solicitors to "take issue" with the Sun newspaper.
"Shearer himself has said that he is happy to stay. He wants to get back to playing for us next season," Walker said. "I can assure you and Blackburn Rovers fans that Alan is going nowhere. We are intending to strengthen our side this summer not weaken it.
"This talk just goes on and on. It causes nothing but trouble for me and the club. We are selling season tickets and it's unsettling. It's just ridiculous.
"We are also looking at the legal side to see if there is anything we can do about it. We want to get this speculation stopped."
Walker is angry that United have made their interest in the England striker known. He has spent almost pounds 60m building up Blackburn and knows that selling Shearer would demolish everything he has taken years putting together.
Alex Ferguson, the United manager, has already had two inquiries turned down and major foreign clubs like Juventus and Barcelona would break the bank for the leading scorer in Euro 96.
Walker went on the offensive after his chairman, Robert Coar, had also denied that United had been in touch.
Martin Edwards, United's chief executive, described the reports that Blackburn would pick up pounds 12m for Shearer, plus United's pounds 7m-rated Andy Cole as "absolute rubbish".
However, he did admit that the club had made a recent offer. "I made an initial approach for Alan Shearer before Euro 96 and Blackburn told us there was no way they would let him leave," Edwards said. "We made a second inquiry and were told the same. There is little else we can do but accept Blackburn's decision."
The reported transfer fee would more than double the British record of pounds 8.5m, which Liverpool paid Nottingham Forest for Stan Collymore a year ago.
Shearer rejected United to accept a more lucrative offer from Blackburn and joined them for pounds 3.3m four years ago. He has scored 37 goals in each of the past two seasons.
The player is saying nothing about the growing battle for his services next season as he prepares for a family holiday in Barbados. Sources close to him suggest he could persuade Walker to let him move abroad to Juventus or another leading foreign side. In Italy his wages would be trebled.
The prospects of Blackburn selling to a domestic rival like United is too much for Rovers to handle emotionally or financially. Since Walker's arrival the club's gates have almost quadrupled. To sell Shearer to United would disillusion that support for good.
Blackburn could justify losing Shearer to Europe and put it down to his own personal ambitions, but letting him join United would be as good as ending Walker's dream of another Premiership title.