A federal judge ruled yesterday that U.S. News and World Report must set aside $29 million plus interest to meet the claims of former employes when it distributes the bulk of the proceeds from last October's $176 million sale of the magazine.

The decision, issued here yesterday by U.S. District Judge Barrington D. Parker, comes in a fiercely contested battle between current and former employes of the news weekly. U.S. News was an employe-owned enterprise until it was purchased by real estate magnate Mortimer B. Zuckerman.

In March, Parker said that all of the sales money could be distributed, but the U.S. Court of Appeals overturned that decision, holding $141 million in a trust account.

In their lawsuit, about 230 former employes, who left the company between 1974 and 1981, allege they are entitled to about $75 million because their shares were intentionally undervalued when they were required to sell them upon leaving the company. The suit says the low appraisals occurred because the company's directors and outside appraisers failed to take into account the true worth of the firm's valuable real estate in the West End area of the District.

In line with the Court of Appeals ruling, Parker said the amount they may "realistically expect to recover" must be set aside, pending a final decision in the case.

John D. Seiver, an attorney for the former employes, called the ruling a "major victory." He estimated that with the interest, the total amount that must be said aside under Parker's preliminary injunction comes to $42.6 million.

Kathy Bushkin, U.S. News's vice president for corporate affairs, said the company "does not disagree" with Seiver's estimate, but declined further comment.