Conservative newspaper publisher William Loeb said today, he has turned over ownership of 75 percent of the Manchester Union Leader to a trust for the sole benefit of his employes.

Loeb, 74, whose editorials have proved a major force in presidential primaries in New Hampshire, said the stock will be held by a trust, administered by his wife, Nackey Scripps Loeb, with the profits going to the paper's employes.

Loeb said he would not be a trustee of the trust or have control over it.

"After I die, I want the paper to be run by people who share the same philosophy that I do, that of public service," Loeb said in a telephone interview with the Associated Press from his home in Prides Crossing, Mass.

He said he had been planning for the "past 30 years" to turn over the paper, New Hampshire's only statewide daily, to employes in a profit-sharing plan. "While I always thought I was immortal, I realized that now that I am 74, I should make it official," he said.

Loeb denied that his action, approved by the paper's board of trustees Friday, had any connection with a U.S. District Court order last month that he sell 25 percent of the paper's stock.

But some observers believe that the trust is an effort by Loeb to retain total control of the paper, by discouraging heavy bidding for the one-quarter share.

Under the settlement of the suit, brought against Loeb for alleged pension law violations, the publisher must sell the 25 percent of the newspaper's stock owned by the pension fund by the end of the year. But if there is no offer higher than $750,000, Loeb could buy it himself.

Investors might be discouraged from buying the quarter share, observers believe, because it might not provide financial gain for several years. Officers of the newly created trust could be expected to invest profits in the newspaper, rather than declare dividends.

On the other hand, the value of newspapers has risen dramatically during the past decade, and there's no telling how long trust officers would refuse offers for a controlling share.

Loeb's financial adviser R. Gary Gomm of San Antonio, Tex., estimated the newspaper's worth at $21.2 million in 1976. Gomm, taking into account the diminished value of minority stock, put the one-quarter share at $2.65 million in 1976. But newspaper industry experts suggest the one-quarter share is worth upward of $5 million now.

Under the transfer of ownership of Loeb's remaining 75 percent, effective immediately, Mrs. Loeb will administer the trust until her death or resignation, when it will be taken over by a designated board of the newspaper's management.

"Since some of the trustees are in their early 30s, I would expect that the newspaper will be run for the next 40 years by men who feel as I do," Loeb said.

After the death of the next to last trustee, the surviving member will oversee the distribution of all the stock held by the trust to the newspaper's employes, Loeb said.