SAN DIEGO — The hotel industry is stepping up its campaign against home-sharing giant Airbnb with the release of a study this month documenting what it says is the rapid rise of “commercial” hosts actively listing multiple rentals on the home-sharing platform.

The study, funded by a foundation arm of the American Hotel & Lodging Association, reports that hosts who rent out two or more whole-home units have become the fastest-growing segment of Airbnb’s business in the U.S.

Last year, such rentals accounted for 40 percent of the company’s national revenue from whole-home listings, or nearly $2 billion, according to the study, prepared by CBRE Hotels’ Americas Research.

In Los Angeles, one of 13 cities specifically studied, the share was even greater — 47 percent — with multi-unit hosts generating nearly $163 million in annual revenues. That represents a year-over-year increase of 87 percent. The study examined a two-year period between October 2014 and September 2016.

The rise of commercial operators, as the trade group calls them, is evidence of Airbnb straying from its roots as a home-sharing platform that allows homeowners a way to earn extra income from renting out a spare bedroom, AHLA said.

“Once upon a time Airbnb might have simply been a home sharing company, but this analysis shows that’s just a fairy tale now,” said Katherine Lugar, CEO of the lodging association. “This report provides a stark contrast to the picture that Airbnb presents to policymakers and the public and sheds light on why the company has largely refused to take even basic steps to stop illegal hotel operators, because these actors drive the overwhelming — and growing — portion of its revenue.”

Lugar said she hopes the industry study will persuade local officials to crack down even more on what she characterizes as illegal hotels and enact regulations to more strictly regulate home-sharing operations.

Airbnb officials quickly dismissed the study, noting that the lodging association’s member inns, motels and hotels also list rooms on the home-sharing platform, which means they would be represented in the data collected by CBRE.

“This misleading, inaccurate report was bought and paid for by the big hotels and is the latest example of the industry’s willingness to say and do anything to protect their record profits, preserve their ability to price gouge consumers and squash their competition,” said Jasmine Mora, an Airbnb spokeswoman.

CBRE included a disclaimer in its study, which relied on data provided by Airdna, a company that tracks Airbnb host listings and revenues.

While CBRE said it believes the data is reliable, it cautions that it has not verified the numbers, saying it is “your responsibility to confirm independently its accuracy and completeness.”

According to Airbnb, 65 percent of its listings in California are for whole-home rentals. In San Diego, it’s 67 percent, and nationwide, the figure is 69 percent, but the company was unable to provide data on the share of hosts operating multiple short-term rentals.

Figures the company provided The San Diego Union-Tribune earlier this month showed that the median earnings of Airbnb hosts in California last year were $9,900.

Increasingly, Airbnb has been battling with cities in the U.S. and globally over local efforts to more strictly regulate short-term rentals, which homeowners claim have disrupted peaceful residential neighborhoods and taken long-term housing off the market. Both San Diego and Los Angeles are expected to act this year on new rules governing home-sharing.

Other key findings noted in the hotel industry study:

All 13 cities studied saw an increase in the total number of listings by multi-unit hosts.

The markets with the highest share of total revenue coming from multi-unit hosts were Miami, Oahu and New Orleans.

In almost every market, the percentage of revenue from hosts operating two or more rentals increased from 2015 to 2016. The exceptions were New York and San Francisco, where tougher regulations have been enacted. 

Revenue growth for whole-home rentals increased on average 76 percent in the 13 cities.