Theater closures across Mexico in an effort to stem the spread of the AH1N1 flu virus are adding to the financial woes of an already beleaguered film industry.

Some 4,369 screens were set to stay dark on what should have been a boffo May 1 Labor Day holiday weekend at the box office.

Mexico’s national film chamber Canacine predicted the industry would take a 268 million peso ($19.4 million) hit with the shuttering of 510 multiplexes nationwide belonging to the Cinepolis, Cinemex, Cinemas Lumiere, MM Cinemas and Cinemark chains. Theaters hope to reopen May 6.

Also taking a hit are some 15,000 theater workers who are losing wages because of the closures, Canacine added.

Mexico is one of the largest foreign markets for Hollywood accounting for about 6% of tickets sold outside the U.S., with much of that money rolling in during the summer months of May, June and July.

With the flu closures and the now much-deeper financial crisis facing the nation, the box office outlook seems grimmer than ever.

In Mexico City, mayor Marcelo Ebrard ordered all non-essential businesses to close from May 1 to May 5 — a holiday weekend built around the May 1 Labor Day observance and the kickoff to the nation’s summer blockbuster schedule.

The majors have stalled the release of “X-Men Origins: Wolverine” and other major tentpoles including “Star Trek” and “Angels & Demons,” potentially costing studios tens of millions of dollars.

For local filmmakers and distributors of Mexican films, the shakeup is likely to make an already packed release schedule that has little room for local pics an even harder environment in which to launch their projects.

The temporary shutdown of most aspects of the capital of 20 million people is likely to affect local film production but to a degree that will only be fully understood after the health crisis winds down.

Mexican film institute Imcine confirmed that at least one feature production has shut down. However, to alleviate the boredom of film fans stuck at home, it has posted a number of shorts online including Guillermo Arriaga’s 2000 pic “Rogelio.”