A minority shareholder in the Des Moines Register and Tribune Co. issued a statement yesterday urging the company's directors to support a sale of the company's operating properties, including the Des Moines Register newspaper, when the directors meet Monday to evaluate several unsolicited offers to acquire the company.

Chicago business executive Fred Eychaner, who owns about 6 percent of the Register and Tribune's stock, was expected yesterday to become at least the fourth bidder to make an offer. Instead, he issued a statement calling for the sale and said he would not make a bid at this time. He also suggested that a 14.3 percent block of Cowles Media Co. stock owned by the Register and Tribune be spun off to company shareholders.

Both the Register and Tribune and Cowles Media Co. are owned primarily by Cowles family members, but the stock of both companies has traded on a limited basis recently. Cowles Media owns the Minneapolis Star and Tribune newspaper.

The Register has a daily circulation of approximately 240,000. The Minneapolis Star and Tribune has a daily circulation of about 373,100.

Both companies have been mentioned as possible takeover targets since Dow Jones & Co., publisher of the Wall Street Journal, and several Des Moines businessmen, including two former Dow Jones employes who are directors and employes of the Register and Tribune, offered $112 million for the company last month. Since that time, Ingersoll Publications, a Connecticut-based newspaper chain, and Ackerley Communications Inc., a Seattle-based communications company, have submitted bids exceeding the Dow Jones offer, with the Ackerley bid at $156 million.

Media analyst Paul Kagan, who said he owns Register and Tribune stock, said yesterday he believes the company is worth $202 a share, or $226 million. Before the Dow Jones offer last month, R&T stock was trading in the mid 30s. Some stock has since traded as high as $120 a share.

Meanwhile, David Kruiden- ier, chairman of both the Register and Tribune Co. and Cowles Media Co., implied to Register employes through casual conversations last week that he wants to reject all offers when the directors meet on Monday. Kruidenier's unhappiness with the bidding war for the company is the principal reason why several major newspaper companies that are interested in acquiring the company have not made formal offers and appear unlikely to bid unless they are invited to do so by the chairman.

Kruidenier told some employes that if a sale of the company becomes inevitable, which becomes more likely as pressure from stockholders to realize the full value of their investment continues to build, the board would consider bids from companies such as The New York Times Co., The Washington Post Co., Times Mirror Co. and Knight-Ridder Newspapers.