Pressure mounted on the National Basketball Association referees to back up their vote to strike next week's playoffs when the National Labor Relations Board said yesterday it would not issue a decision before Monday on the merits of charges of unfair labor practices by the NBA.

The delay by the NLRB was seen as a benefit to the league, which has refused to negotiate a new contract with the officials. The referees, whose contract expires at the end of the regular season Sunday, had hoped to get the league to the bargaining table with a favorable NLRB ruling.

The playoffs start Tuesday.

Now, the pressure is squarely on the officials. If they follow through with Monday's strike vote, they face the prospect of not being rehired. In the past, the NBA has arbitrarily fired officials at the conclusion of each season and the refs have no grievance procedure.

In New York, NBA deputy commissioner Simon Gourdine said, "I hope they (the officials) think it through before they do anything."

Following the strike vote the NBA has been assigning two standby referees to each league game.

Darrel Garretson, a 10-year NBA official and executive director of the National Association of Basketball Referees, said yesterday the the referees have no meeting planned to reconsider their unanimous vote to strike.