Hundreds of US entertainment workers rallied outside the New York headquarters of Amazon and HBO on Tuesday in a National Day of Solidarity with the strike that has shut down Hollywood.

Waving placards and chanting through megaphones, the demonstrators vowed to continue the industrial action that has brought America's entertainment industry to a standstill since May until their demands are met.

"The movement has not stopped, the movement has only grown," said Ezra Knight, president of the New York branch of the actors' union SAG-AFTRA, adding: "We're still here, we're still fighting."

The Writers Guild of America (WGA) walked out in May, and were joined on the picket lines by the far larger Screen Actors Guild last month.

The twin actions have halted film and TV production and forced a postponement of the Emmy Awards.

The unions are demanding better pay, guarantees to limit the use of artificial intelligence, and other improved working conditions.

The WGA announced earlier this month that it was returning to the collective bargaining table after studios requested a meeting to explore ways to end its strike.

The WGA said it had accepted a request to meet with the Alliance of Motion Picture and Television Producers (AMPTP), which includes studios like Disney and Netflix.

"(That) means there may be hope, for us, too, because it means the AMPTP has started to rethink things, and come to the table with an idea and a bargain," said Knight.

Actress Laura Houha said she hoped to have been back at work by now.

"Hopefully the loud sounds that we're making are being heard by the powers that be and they're seeing that there's more of us than there are of them," said the 34-year-old.