Walt Disney Co on Thursday postponed the debut of its movie "Mulan" indefinitely, dealing a new blow to theater operators that were counting on the live-action epic to help attract audiences during a pandemic.

ViacomCBS Inc's Paramount Pictures also said "Top Gun: Maverick", the much-awaited sequel to the Tom Cruise-starring "Top Gun", has been delayed to July 2, 2021 from December 23, 2020.

"Mulan" was scheduled to reach theaters in March but its release has been postponed several times as many cinemas remain closed. The film had most recently been set to debut on Aug. 21 and theater operators had hoped it would help spark a late-summer rebound for movie-going.

Disney also said it had delayed the next film installments from two of its biggest franchises, "Avatar" and "Star Wars," by one year as the novel coronavirus has disrupted production.

The "Avatar" sequel is now set to debut in theaters in December 2022, and the next "Star Wars" movie in December 2023.

"It’s become clear that nothing can be set in stone when it comes to how we release films during this global health crisis," a Disney representative said. "Today that means pausing our release plans for 'Mulan' as we assess how we can most effectively bring this film to audiences around the world."

The "Mulan" delay follows Warner Bros decision to postpone the August release of Christopher Nolan thriller "Tenet." The two films were seen as theaters' best chance to salvage part of the lucrative summer season.

The AMC and Cineworld movie theater chains on Thursday pushed back the reopening date for their U.S. theaters to at least mid-August from the end of July.

The "Avatar" delay also removes one of next year's biggest movies.

The follow-up to James Cameron's 2009 blockbuster that is the second highest-grossing film of all time, "Avatar 2" had faced numerous delays even before the coronavirus outbreak. At one time it had been expected to reach theaters in 2014.

Disney has not released details on the next "Star Wars" film.