"It is a clear violation of federal law for the AMPTP (the Alliance of Motion Picture and Television Producers) to issue an ultimatum and break off negotiations if we fail to cave to their illegal demands," the WGA said in a statement.

Negotiations broke off Dec. 7 when the alliance refused to bargain further unless the WGA dropped a half-dozen proposals that included the authority to unionize writers on reality shows and animation projects.

The WGA urged the alliance to return to the negotiations immediately despite of the ongoing holiday season so that "this town can be put back to work."

But producers blasted the complaint as an act of desperation.

"The WGA's filing of a complaint with the NLRB reminds us of the old lawyers' adage: When the facts are on your side, argue the facts. When the law is on your side, argue the law. And when you don't have either the law or the facts on your side, you pound the table," the AMPTP said in a statement.

"The WGA has now been reduced to pounding the table, and this baseless, desperate NLRB complaint is just the latest indication that the WGA's negotiating strategy has achieved nothing for working writers."

"All of us -- producers, directors, writers and everyone working in the entertainment business...must work in partnership to create a modern economic system that fairly shares the benefits of progress while providing opportunity for the kind of innovation and flexibility we all need to succeed," the AMPTP said.

The writers' strike began on Nov. 5, with the dispute focusing on residual payments to writers for work distributed via the Internet, video iPods, cell phones and other new media.

In other developments, the Directors Guild of America announced that it may begin negotiating a new contract with the AMPTP in January. Those talks will likely be focused on many of the same issues the WGA is arguing about.