LONDON — On Dec. 5, “Six” — the hit show about the wives of Henry VIII — staged a triumphant comeback when it became the first musical to be staged in London’s West End since the coronavirus pandemic began in March.

Now, just nine days later, that comeback has been brought to a sharp halt.

Matt Hancock, Britain’s health secretary, announced on Monday that the government was tightening restrictions in London, as well as other parts of southern England, because of a “very sharp, exponential rise” in coronavirus cases. The new restrictions, which include a ban on theatrical performances and the closure of other indoor cultural institutions, like museums, would take effect Wednesday, he added. Pubs and restaurants would also close, though they could still offer takeout.

“For businesses affected, it will be a significant blow, but this action is absolutely essential,” Hancock said, addressing Britain’s Parliament.

Many theaters in London have been closed since the beginning of the pandemic, in March, though some smaller shows returned in the summer, with reduced audiences and socially distanced performers.

In November, some major productions, including “Six,” were slated to return, but the British government announced a national lockdown that scrapped their plans.

That lockdown lifted on Dec. 2 and England moved to a tiered system of restrictions, with differing rules around the country, including for cultural events.

Monday’s announcement that London would move to “tier three,” the highest level of restrictions, was “devastating for the city’s world-leading theater industry,” Julian Bird, chief executive of the Society of London Theatre, said in a news release.

“The past few days have seen venues beginning to reopen with high levels of Covid security, welcoming back enthusiastic, socially distanced audiences,” he added. Theaters across London “will now be forced to postpone or cancel planned performances, causing catastrophic financial difficulties for venues, producers and thousands of industry workers,” he said.

Several theater producers echoed those comments in statements. The closure was “a hammer blow to an industry which has been fighting valiantly to bring culture and community to people’s lives this Christmas,” Louis Hartshorn and Brian Hook, the producers of “The Great Gatsby,” said in a joint email.

Britain’s government had “created a situation where millions of pounds have been spent on re-launching productions and shut them down just as revenue is about to be generated,” the statement added.

Many theaters had begun presenting holiday fare, including several pantomimes, a particularly British theater form, popular at Christmas: The National Theater’s production “Dick Whittington” opened on Friday, and “Pantoland,” at London Palladium, began its run on Saturday.

Kenny Wax, one of the producers of “Six,” said in a telephone interview that he felt “incredible disappointment for everyone who’s worked so hard” to bring shows back to the West End after the national lockdown.

Wax said he expected the closure in London would last at least four weeks. During that time, workers on his productions were unlikely to be paid, he said, adding that to do that without revenue coming in from ticket sales would bankrupt his company. But he said he hoped to get his shows back on as soon as possible to get money flowing to the many freelance artists who work on “Six” — not just the actors, but the musicians, technicians and ushers.

“If from now it’s ‘a few weeks on, a few weeks off,’ we’ll probably keep doing that,” he said. “We’ll keep trying.”