Unions representing printers and pressmen at The Washington Star entered an 11th-hour round of negotiations with the newspaper's management last night under The Star's threat to close at noon today unless labor agreements are reached.

"I would say that the sides are far apart at this juncture," Kenneth E. Moffett, deputy director of the Federal Mediation and Conciliation Service, said at a news conference yesterday afternoon. "We are probably going to be up most of the night." The negotiations have taken place at the mediation service headquarters.

Moffett noted, nevertheless, that some "movement" had occurred in The Star's talks with the printers' and pressmens' unions and at once point said, "We're hopeful."

By early yesterday evening all nine other unions representing Star employes were reported to have completed tentative or final agreements on new five-year contracts with the newspaper. Time Inc., the publishing company that purchased The Star earlier this year, has announced it will shut down the newspaper today unless all 11 unions representing 1,270 full-time Star employes have signed stringently modified new agreements.

Two major unions-Mailers Local 29 and Teamsters Local 639-reached accords with The Star during yesterday's intensive bargaining sessions, according to federal mediators. The Teamsters local represents delivery truck drivers and other blue-collar workers. The Mailers union includes employes who bundle and sort newspapers for delivery.

Judge Charles R. Richey, who had previously set a deadline of 4 p.m. yesterday for the negotiations between The Star and its employe unions, extended his deadline until 10 a.m. today. Richey announced in U.S. District Court Friday that if the newspaper and the the unions failed to reach agreements by his deadline, he would consider issuing a temporary restraining order to prohibit The Star from closing.

Moffett said Richey had agreed to extend his deadline at the federal mediation service's request. Richey was unavailable for comment yesterday, but his office confirmed that the deadline had been changed to 10 a.m.

The printers' local-Columbia Typographical Union No. 101-asked Richey to issue an injunction last week, contending that The Star's threat to close violated provisions of an existing labor contract and that the issue of whether The Star may close and discharge its employes is subject to arbitration. Richey has postponed ruling on the union's request, saying he would prefer the union and management to reach a settlement without a court order.

The labor dispute between the typographical union, which represents about 175 Star printers, and the newpaper's management centers on The Star's proposal to eliminate 80 printing jobs by June an to reduce the newspaper's printing staff to as few as 25 employes during the next five years.

Union leaders have contened that, under The Star's proposal, many union members would be "forced" to give up their jobs and that such compulsory layoffs would abrogate parts of the union's existing contract with The Star, which guarantees lifetime jobs for printers. The Star's management has proposed to offer "buyouts," amounting to $40,000 each, to any printer who quits.

The pressmen's union-Newspaper and Graphic Communications Union Local 6-has remained in sharp disagreement with the newspaper's management over The Star's proposals to alter "manning" rules governing the number of pressmen assigned to operate a press, according to union and other officials. Reductions in "manning" would result in losses in pay or possible layoffs, according to officials familiar with the negotiations. Local 6 represents about 85 Star pressmen.

The federal mediation service sought to step up pressure for settlements in the remaining labor-management disputes yesterday by calling top Star officials and leaders of most Star Employee unions to two meetings at the mediation service is headquarters. Another such meeting is scheduled for 9 a.m. today.

Moffett, who helped mediate regent strikes at New York City newspapers and acted as the chief spokesman for all sides in yesterday's negotiations, said that his newly concluded agreements by the Teamsters and Mailers locals were "bound to have some effect" on The Star's talks with the printers' and pressmens' unions.

Teamsters Local 639 announced tentative agreements on two new contracts early yesterday afternnon and scheduled ratification votes for this morning. One of the tentative agreements covers about 40 "jumpers," who carry newspapers from delivery trucks to vendors. The other would apply to more than 100 drivers, loaders, helpers and other blue-collar workers. The Teamsters local has already ratified a third contract covering nearly 300 circulation route managers.

No terms of th two tentative Teamsters accords were disclosed yesterdays. Teamsters leaders have previously said wages represented the key issue in bargaining over the two contracts.

A contract agreement was reached ywesterday afternoon between The Star and Mailers Local 29, which represents about 70 Star employes. The accord was ratified last night by about a 2-to-1 margin, according to a federal mediation service spokesman.

According to a reliable source, a key issue in The Star's negotiations with the Mailers union was a Star proposal permitting possible subcontracting by the company for similar work-a plan that could lead to a loss of some jobs for union employes. Terms of the Mailers agreement were not immediately made public.

Star officials did not comment publicly yesterday on the negotations. Moffett said the newspaper's management had indicated "no change" in its deadline for completing negotiations to replace all 14 contracts it currently has with its employes' 11 unions.

Although all 14 existing labor contracts are scheduled to remain in effect until late next year, The Star has sought to obtain new contracts partly in an effort to guarantee five years of labor stability. Star officials have said that the newspaper lost $7.2 million during the first 11 months of 1978 and that it expects to run a $16 million deficit next year. Time Inc. has pledged to invest $60 million in the newspaper over the next five years if new contracts are completed with the unions by today.

According to Moffett, the printers' union has scheduled a meeting for 2 p.m. today to report to its members on the outcome of its negotiations, with the Star. Moffett said he knew of no similar meering for pressmen's union members.