Labor talks between The Washington Star and its guild unit soured yesterday, following what the union considered a threat by the board of directors of Time Inc., The Star's parent company, to close the paper unless new contracts are signed by Dec. 31.

The snarl in the negotiations came less than weeks after The Star's 11 unions agreed, at management's request, to reopen their contracts at least one year before some of them were due to expire.

Time, which bought The Star for $20 million earlier this year, has announced plans to invest $60 million but also is seeking certain concessions from the unions, including greater management freedoms, reductions in some jobs and improved productivity.

At a meeting Wednesday, Star Publisher George W. Hoyt told union representatives that The Star has "no authorization to expect funds after Dec. 31 without new contracts being ratified by the unions."

Union leaders interpreted this statement as a threat to close the paper if the unions do not sign new contracts by the year's end.

Yesterday, Local 35 of the Washington-Baltimore Newspaper Guild, which represents The Star's editorial and commercial employes, called a special membership meeting to denounce Time's position. The union released this statement:

"The membership of the Star unit of the guild is outraged by management's arrogant insensitivity to its obligations to its employes and its lack of moral duty to negotiate openly and in good faith. The union will not be intimidate by such dictatorial displays of corporate power.

"We will pursue all our legal remedies while we continue to insist that management begin meaningful collective bargaining toward a new or extended contract. We consider curious management's claim that Time Inc. is unable to continue publication of a daly newspaper in the nation's capital after only eight months of trying."

Asked last night to comment on the guild's resolution. Hoyt said he had no further statement to make. "Any further comment by management would not be in the best interest of the negotiations," he stated.

None of The Star's other unions has issued a statement since last Wednesday's meeting with the paper's management.

Before accepting to reopen their contracts, the unions requested and received a letter from management promising that if the current talks fail, the paper would honor the old contracts.

Ray. Dick, representative for Local 35, said his union and the others had therefore figured there was nothing to lose by agreeing to negotiate early with The Star. But in light of Hoyt's comments Wednesday, Dick sounded pessimistic about the talks.

"We feel it was a serious breach," he remarked. "We could understand the logic of reopening the talks. But in view of what has been said, we feel it's like holding a gun to our heads."