Facing possible layoffs of almost one-quarter of their staff, three of the four top editors at United Press International announced their resignations yesterday, saying they could "no longer assure the quality and integrity of the UPI report."

The three editors, who were protesting financial cutbacks by UPI owner Mario Vazquez Rana, were Ben Cason, the wire service's editor; Barry Sussman, managing editor for national news, and Kim Willenson, managing editor for international news. Bill Ferguson, UPI's managing editor for broadcast news, did not join in the resignations, which are effective Nov. 20.

Claude Hippeau, UPI's executive vice president, said in a statement that UPI's management "deeply regrets" the resignations and expects to announce a new editorial management team "shortly."

UPI spokesman Christopher Smith denied rumors that the news service was for sale or that Vazquez Rana planned to close the long-troubled news agency.

Although the three editors declined to discuss details of their differences with Vazquez Rana, UPI sources said the Mexico City businessman -- who bought UPI in the summer of 1986 -- had taken away the editors' authority to make even the most routine decisions about how to spend the wire service's funds. One mid-level editor said that approval was required from Vazquez Rana's office in Mexico City even for $100 expenditures for reporters trying to cover stories.

"Control was removed from our hands. Mario Vazquez Rana is making all the decisions," Willenson told a meeting of UPI's Washington staff after the resignations were announced.

The three editors told the staff they had not had any "meaningful" communications with Vazquez Rana for several weeks.

One UPI source said the three editors were advised in writing recently that Vazquez Rana planned to curtail his financial contributions to UPI -- a scaling back of funds that would result in the layoff of about 300 of UPI's 1,250 employes.

"We were asked to stay and supervise the layoffs, and we would not do that," Cason said at the staff meeting.

However, UPI spokesman Christopher Smith said the company "has made repeated official statements that there are no plans for layoffs of any full-time permanent employes."

Smith said UPI was losing about $1 million a month, although other sources at the wire service estimated monthly losses at between $1.5 million and $2 million.

Sources at UPI said Cason, Sussman and Willenson submitted their resignations about 10 days ago. The editors said they had not spoken to Vazquez Rana since resigning.

When word circulated at UPI about the pending departures, a group of UPI's middle managers called an emergency meeting with a Vazquez representative in Washington last Thursday. In a memo dated the next day, these key regional managers said they were concerned about immediate threats to UPI's survival as "a viable news service or as a salable property."

The memo complained about the nonpayment or slow payment of bills, that the middle managers said is "paralyzing UPI operations and hopelessly tarnishing the international image of the company and its leader." The managers noted that telephone companies were threatening to cut off UPI's services in some bureaus and that other bills were not being paid on a timely basis, just as in 1984 when UPI was being reorganized under Chapter 11 bankruptcy proceedings.

"We should not be in a situation whereby UPI, as was the case in 1984, is perceived as a bunch of deadbeats, a collection of people who don't pay their own way, who let their stringers go without compensation and allow their phone lines to be cut," said the memo signed by Lucien Carr, assistant managing editor for national news; David Tucker, the sports editor; Jacques Clafin, manager of UPI's Los Angeles bureau, and James F. Wieck, regional editor for the Southwest division.