(Recasts throughout, adds SAG-AFTRA comment paragraphs 6-7, joint statement paragraph 13)

By Lisa Richwine

LOS ANGELES, June 30 (Reuters) - Hollywood's actors union and major Hollywood studios agreed on Friday to keep negotiating through mid-July, staving off the immediate threat of a second labor strike in the entertainment business this summer.

The SAG-AFTRA union and the Alliance of Motion Picture and Television Producers (AMPTP) said they would extend their current contract, which had been set to expire at midnight, through July 12.

The agreement gives the two sides more time to work out a deal and prevent a work stoppage that would have added to ongoing labor strife in Hollywood. Members of the Writers Guild of America (WGA) walked off the job on May 2, forcing many film and TV productions to shut down.

A-list stars including Jennifer Lawrence and Meryl Streep, in a letter to union leadership this week, said they were ready to walk off the job if negotiators failed to reach a "transformative deal" on higher base pay and safeguards around use of artificial intelligence (AI).

The letter came days after union negotiators issued a video saying their talks had been "extremely productive," a possible sign that a deal was within reach.

In a message to members on Friday, SAG-AFTRA's negotiators they had unanimously agreed to the contract extension "in order to exhaust every opportunity to achieve the righteous contract we all demand and deserve."

"No one should mistake this extension for weakness," they said.

SAG-AFTRA voted in early June to give its leaders the authority to call a work stoppage if talks were to break down.

Negotiations were taking place during a difficult time for Hollywood studios. Conglomerates are under pressure from Wall Street to make their streaming services profitable after pumping billions of dollars into programming to attract subscribers.

The rise of streaming has eroded television ad revenue as traditional TV audiences shrink.

The walkout by 11,500 writers has shut down a wide swath of TV production and delayed the filming of movies including Marvel's "Thunderbolts" and "Blade." Any ongoing filming would have to halt if actors also strike.

Leaders of SAG-AFTRA, which represents 160,000 actors, and the WGA say the entertainment industry has changed dramatically with the rise of streaming television and the emergence of technology such as generative AI, which they fear could be used to write scripts or create digital actors.