Ric Francis, Associated Press
People load picket signs into vans at the Writers Guild of America headquarters Sunday in Los Angeles. Hollywood writers are set to strike against TV networks and movie studios over writers' share of profits from DVDs and the Internet.

LOS ANGELES — Under the eye of a federal mediator, Hollywood's writers and producers resumed talks toward a new contract Sunday as a midnight strike deadline drew near.

As of late afternoon, there was no sign of a breakthrough. More than 12,000 screenwriters represented by the Writers Guild of America West and the Writers Guild of America East prepared to begin the first industry-wide strike since writers walked out in 1988. That strike lasted five months and cost the entertainment industry an estimated $500 million.

After more than three months of acrimonious negotiations, a contract between the unions and the Alliance of Motion Picture and Television Producers — which represents networks, studios and other producers — expired last Wednesday night. Guild leaders called for a strike to begin Monday morning. A federal mediator, who joined the talks last week, asked the sides to continue talking in a Sunday session.

Throughout the weekend, guild leaders held orientation meetings for strike captains, who would supervise picketing teams, and otherwise prepared for an attempt to shut down as much movie and television production as possible. Spokespeople for the producers and writers declined to comment on the talks on Sunday.

The Writers Guild of America East announced Sunday that beginning at 9 a.m. Monday hundreds of its members would picket outside Rockefeller Center, with its cluster of major media companies in the neighborhood. And picketers here are expected to march outside more than a dozen studios and production sites in four-hour shifts, one of which will begin at 9 a.m. Monday, the other at 1 p.m.

The sides have been at odds over, among other things, writers' demands for a sharp increase in pay for movies and TV shows used on DVDs, and for a bigger share than producers are willing to pay of the revenue from such work when it is delivered over the Internet.