A dozen of Hollywood's highest-earning stars, from George Clooney to Meryl Streep, have each donated $1 million or more to support out-of-work actors as their strike enters its fourth week, their union's charitable foundation said Wednesday.

The Screen Actors Guild (SAG-AFTRA) walkout, and another strike by film and TV writers that began in May over pay and the threat of artificial intelligence, have brought US film and television production to a halt.

The Hollywood "double strike" of writers and actors -- the first since 1960 -- has cost the entertainment industry and the California economy several million dollars per day, as well as costing the striking unionists their paychecks.

But wealthy A-list celebrities, from Clooney and Streep to Matt Damon, Leonardo DiCaprio and Dwayne "The Rock" Johnson, as well as Nicole Kidman, Julia Roberts, Oprah Winfrey and others, have each contributed $1 million or more to the SAG-AFTRA Foundation's actors' support fund.

The nonprofit foundation has raised more than $15 million in the past three weeks to aid "thousands of journeymen actors" facing economic hardship, it said in a statement.

"The entertainment industry is in crisis and the SAG-AFTRA Foundation is currently processing more than 30 times our usual number of applications for emergency aid," Courtney B. Vance, the foundation's president, said in the statement.

The organization's aid program is meant to "ensure that performers in need don't lose their homes, have the ability to pay for utilities, buy food for their families, purchase life-saving prescriptions, cover medical bills and more," Vance said.

While some actors are highly paid, SAG-AFTRA president Fran Drescher said this week that 86 percent of the union's 160,000 members earn less than $26,500 a year, The New York Times reported.

The strikes have meant movie productions are shut down, glitzy premieres are scrapped, and events such as the Emmys are delayed as stars are banned from promoting TV shows.

The unions' demands have focused on higher pay in the streaming era and the threat posed to members' careers and future livelihoods by artificial intelligence, while studios say they must cut costs to cope with economic pressures.

While the writers' union appears poised to return to talks on Friday, actors remain at an impasse with major firms such as Netflix and Disney, which are represented by the Alliance of Motion Picture and Television Producers (AMPTP).

"We have not heard from the AMPTP since July 12 when they told us they would not be willing to continue talks for quite some" time, SAG-AFTRA chief negotiator Duncan Crabtree-Ireland told trade outlet Deadline this week.