By Erich Schwartzel

Walt Disney Co. is delaying the reopening of its Disneyland Resort, the company said Wednesday, postponing a crucial element of its plan to get back to business following months of closures.

The park, which had been scheduled to reopen on July 17, will now stay closed until an unspecified date.

Disney said the delay was prompted by state officials. who aren't planning to issue guidelines for theme-park reopenings until after July 4.

"Given the time required for us to bring thousands of cast members back to work and restart our business, we have no choice but to delay the reopening of our theme parks and resort hotels until we receive approval from government officials," the company said.

Disney has faced mounting criticism from employees who say the rising number of coronavirus cases in California has made it dangerous to go back to work.

The decision to delay the reopening of one park is likely to ripple throughout the company and on Wall Street, emboldening workers at Walt Disney World who want to postpone their return and calling into question Disney's timeline for parks revenue to start flowing again. Disney has already lost billions of dollars in revenue from the park closures.

The Downtown Disney retail area surrounding Disneyland is still scheduled to open on July 9.

Similar concerns about returning to work have been growing among the employees at Walt Disney World in Orlando, Fla., which is scheduled to reopen in phases starting on July 11. Online petitions have circulated among employees and the public, and a protest was scheduled near Disneyland for Saturday.

Disney has had to convince local and state officials regarding its reopening plans. The parks division is planning to limit capacity at the reopened attractions and enforce social-distancing rules. Guests and workers will be required to wear a mask and are subject to temperature checks before entering the parks.

Other parts of Disney have had to question plans to restart operations as the number of virus cases ticks upward. The company's studio division is considering postponing the release of its movie "Mulan," which had been scheduled to hit screens on July 24 as the first major Hollywood offering since the pandemic shut down theaters.

Write to Erich Schwartzel at erich.schwartzel@wsj.com