A report released Monday found that thousands of Airbnb units are illegally hogging the city’s supply of vacant apartments.

The study issued by Share Better, a staunch opponent to the online short-term listing site, said that more than 28,000 Airbnb listings, about 55% of all New York City offerings, constitute entire apartments, which violates housing regulations.

In addition, there were 8,058 illegal Airbnb pads that were identified as “impact listings,” meaning they were offered for rental by hosts who have more than one unit for multiple short-term users over the course of at least three months per year, or a single unit for at least six months per year.

Public Advocate Letitia James, who rallied with other elected officials and housing advocates on the steps of City Hall Monday, said there needed to be more oversight of the business.

“Airbnb’s practices are swallowing up affordable housing units,” she said in a statement.

The study, commissioned by non-profits Housing Conservation Coordinators and MFY Legal Service, analyzed data from Airdna, a third-party source that tracks Airbnb listings, between January and December 2015, and other resources, such as the U.S. Census and the city.

The New York State Multiple Dwelling Law prohibits the renting out of apartments within buildings with three or more units for less than 30 days, unless the owner or a family member is present. Last week, the State Legislature passed a bill that would fine Airbnb users who post such listings up to $7,500 and it is awaiting a final signature from the governor.

The “impact listings” were heavily concentrated in several neighborhoods in Manhattan and Brooklyn, such as Greenwich Village, Chelsea, Williamsburg and Bedford Stuyvesant, which have seen huge increases in rent between 2011 and 2015. In fact, the average rent for the top 20 Airbnb neighborhoods shot up 17% during that time period compared to the citywide average of 10%. As the prices went up, so did the number of listings, according to the report.

Airbnb refuted the claims by Share Better, contending that their listings are legal and 72% of New York hosts are “low, middle or moderate income earners.” Airbnb spokesman Peter Schottenfels said that many of their hosts avoid foreclosure and other financial problems thanks to the service.

“They made targeting middle class people their top priority,” he said in a statement. “We need to work together to find solutions that actually benefit middle class New Yorkers, including how to protect responsible home sharers.”

Krishna Rao, an economist with the real estate listings site StreetEasy, said the report raises important questions, though there are many factors beyond Airbnb playing into the city’s housing shortage.

The internet beyond Airbnb has been used for years to skirt state laws and offer short-term spaces, he said.

“The report tries to highlight the activity of Airbnb but it’s a taller task to paint how New York City would look without Airbnb,” he said.

New Yorkers have traditionally divided among those who want the help with their rent and those who find the influx of strangers a nightmare.

Sonya Miranda, 70, of the East Village said the rents are rising too much in the area and tenants must do what they can to make ends meet.

“If they have spaces to rent out, why not rent out to survive in the city?” she asked.

Michelle Guillen, 45, on the other hand, said she has seen many Airbnb visitors in her East Village building and their hosts have little regard for their neighbors.

“Why should we be subjected to the renters? There’s loud noise, cigarette smoke, and trash,” she said. (With Yeho Hwang)