Gus Ruelas, Associated Press
Writers from the Writers Guild of America arrive during a WGA meeting at the Los Angeles Convention Center, where negotiators are trying to arrive at a last-minute deal.

LOS ANGELES — Hollywood writers will begin a strike Monday morning unless the writers and studios can agree on a last-minute deal for a new contract over the weekend, union officials said Friday.

The announcement was posted on a Writers Guild of America Web site.

It said the walkout would begin at 3:01 a.m. EST and all work by members had to cease. More details were promised over the weekend.

It would be the first strike in nearly 20 years for the Writers Guild of America.

The union's board made the announcement after meeting to approve the timing of the strike, which was first disclosed on Thursday night at a meeting attended by 3,000 members.

Union leaders said they would delay the action if producers showed movement in contract negotiations — especially on the key issue of paying writers when TV episodes are sold or streamed over the Internet.

Nick Counter, president of the Alliance of Motion Picture and Television Producers, said his group was ready to meet and finish negotiations over the weekend.

The first casualty of the strike will likely be late-night talk shows, which are dependent on current events to fuel monologues and other entertainment.

The strike will not immediately impact film or prime-time TV production.

Most studios have stockpiled dozens of movie scripts, and TV shows have enough scripts or completed shows in hand to last until early next year.

About 3,000 of the union's 12,000 members attended Thursday's meeting.