The Simon Wiesenthal Center, a prominent human rights organization, on Wednesday sued one of the world’s largest insurance firms, Chubb, for denying coverage of losses the center claims to have suffered because of coronavirus restrictions, the latest skirmish in a growing conflict between insurance companies and policyholders.

The two rabbis who lead the organization castigated Chubb for denying their insurance claims, writing in a statement that Chubb’s behavior was “categorically immoral and unjust.”

The suit is part of a battle that has erupted over whether insurance providers should have to pay “business interruption” claims to organizations and companies that have shuttered because of the coronavirus.

Chubb and other major insurers have said that business interruption policies generally do not cover losses associated with pandemics or viruses and noted that many policies specifically exclude such coverage.

The Wiesenthal Center and dozens of other customers say there was no such exclusion in the policies they purchased. The center said it is still calculating losses from the cancellation of major fundraisers and other events over the past six weeks, including one scheduled for Wednesday commemorating the 75th anniversary of the liberation of the Dachau concentration camp.

“We were shocked to hear that our policy, which we have paid over decades,” will not be honored, Rabbi Marvin Hier, dean of the center, said in an interview, adding that the policy held by the nonprofit has no virus or pandemic exclusion.

The center’s associate dean, Rabbi Abraham Cooper, called the issue “a matter of basic fairness.” For Chubb to deny claims from the center and other policyholders “is the height of chutzpah and hubris,” he said.

A Chubb spokesman declined to comment on the dispute, because it is under litigation.

The Wiesenthal Center, which studies the lessons of the Holocaust, filed its suit in federal district court in Los Angeles. The nonprofit organization is represented by New Orleans lawyer John Houghtaling, who co-founded a coalition of unhappy insurance clients, dubbed the Business Interruption Group.

The lawsuit seeking a declaratory judgment that the claims are valid is the latest of dozens of legal actions filed in a conflict pitting the country’s powerful insurance industry against restaurants, hotels, Main Street businesses and now some nonprofits.

The altercation has attracted the interest of President Trump, who has said that insurance companies should pay legitimate claims, and has set off a massive lobbying campaign in Washington, where some insurers are making the case that the federal government needs to step in and provide financial help to businesses suffering because of the pandemic.

The industry’s powerful lobbyists, led by the American Property Casualty Insurance Association (APCIA), say business interruption policies never were intended to cover contagions. Even if they had been, lobbyists say, the estimated claims just from small businesses during the coronavirus pandemic could total more than $430 billion a month, threatening to create a “solvency event” for the industry.

In an April 21 Wall Street Journal opinion piece, Chubb chief executive Evan Greenberg wrote that “viruses are not covered” by business interruption insurance.

In the piece, Greenberg decried the impact of the virus on the insurance industry’s bottom line. “The coronavirus pandemic imposes a heavy burden on the insurance industry,” Greenberg wrote, warning of the cost of litigation. “Our balance sheets will also be hit.”

Wiesenthal officials claim that Greenberg appeared to indicate the opposite the following day on a call with investors, saying the company was in a good position to weather the crisis.

“It will not threaten our balance sheet. . . . We have a very strong balance sheet,” he said on the call, according to a transcript. “Our capital and liquidity position are robust.”

Greenberg responded to questions about business interruption claims on the call by noting that the industry trade association and regulators have said that viruses and pandemics generally are not covered.

“Lawyers and the trial bar will attempt to torture the language on standard industry forms and try to prove something exists that actually doesn’t exist and try to twist the intent when the intent is very clear,” Greenberg said. “And the industry will fight this tooth and nail. We will pay what we owe.”

The Wiesenthal Center said Greenberg’s comments to investors revealed that the “insurance industry is concealing its fiscal health with threats of insolvency.”

A Chubb spokesman said that Greenberg’s statements were consistent, noting the chief executive has said in the past that insolvency was a risk if insurance contracts were retroactively changed to require payment of pandemic-related claims.

The Wiesenthal Center joins a growing list of companies putting pressure on the insurance industry. The Business Interruption Group has been led by celebrity chefs including Wolfgang Puck, Thomas Keller of Napa Valley’s French Laundry restaurant and Jean-Georges Vongerichten, who owns a restaurant bearing his name at Trump Tower in Manhattan.

On March 29, the top chefs made their case to the president directly during a conference call, stressing that insurers needed to pay up, according to people familiar with the call, who spoke on the condition of anonymity because they were unauthorized to comment on it.

Days later, Trump surprised the industry, saying at the daily White House coronavirus briefing that he thought insurers should pay business interruption insurance claims if the policies did not include a pandemic exclusion, noting that insurance customers had paid their premiums for years.

“When they finally need it, the insurance companies say we are not going to give it,” Trump said. “We cannot let that happen.”

A White House official confirmed the call, adding that the National Economic Council is studying the matter.

Meanwhile, insurance industry lobbyists have joined with dozens of trade-group allies to call for a government assistance program to deliver aid directly to businesses, including through a federal fund modeled in some ways on the aid that was provided after the 9/11 attacks.

The insurers’ preferred proposal competes with several other efforts emerging on Capitol Hill, including an early push by Rep. Brian Fitzpatrick (R-Pa.) to force insurers to pay businesses disrupted by the coronavirus.

Another, from Rep. Mike Thompson (D-Calif.), would ensure that future business interruption coverage includes pandemics — an idea that APCIA and its allies said in an April letter would “end the very existence of the business interruption insurance market as we know it.”