Mayor Bill de Blasio has called for reforms of an “exploitative” charter bus industry following the fatal Queens crash that killed three on Monday.

Though a federal investigation into the cause of the crash is ongoing, de Blasio on Wednesday said industry labor issues lead drivers to work long hours for little pay and incentivize lengthy, dangerous shifts.

“From what I can see, it’s an exploitative industry that needs to be reined in,” said de Blasio at an unrelated news conference in Gowanus, Brooklyn. “I fear what’s going on here is an industry that is really unfair to its workers and exploitative and forces workers to work unusually long hours without additional benefits.”

De Blasio’s labor concerns align with those of union reps who are pushing for federal and state regulators to mandate better pay and other benefits to keep drivers from taking on marathon shifts.

“These buses are sweatshops on wheels,” said Larry Hanley, the international president of the Amalgamated Transit Union, a labor organization representing bus drivers. “There is rampant fatigue in the industry caused by low wages … it’s a third world form of transit that exists in the United States.”

On Monday morning, officials said Raymond Mong, 49, drove a Dahlia charter bus through a red light along Northern Boulevard at about twice the posted speed limit, crashing so forcefully into a turning MTA bus at the intersection of Main Street that the MTA bus spun around. Mong, who died in the crash, also crashed his bus into a nearby storefront.

Both Mong and the company he worked for had a record of dangerous driving. Mong lost his job as an MTA bus driver in 2015 after he was arrested and charged with driving under the influence and fleeing the scene of a crash in Connecticut.

The Flushing-based Dahlia Group Inc. has received seven unsafe driving violations since September 2015, four of which were for speeding, according to federal data. Two of those speeding violations were for buses traveling more than 15 miles per hour above the posted speed limit.

At the time of Monday’s crash, Mong was properly licensed by the state, though he was working illegally for Dahlia. The company failed to inform the DMV that Mong had been hired as a driver — as required by state law, according to the state’s Department of Motor Vehicles and the National Transportation Safety Board.

NTSB, the federal agency leading the investigation into Monday’s crash, is testing toxicology samples and reviewing Dahlia’s log books to confirm if Mong had been under the influence or working long hours at the time of the crash, according to Robert Accetta, NTSB’s investigator in charge.

De Blasio said Dahlia was not “responsible” in its operations, but ultimately blamed an industry that is predominantly governed by state and federal regulations. He cast doubt that the investigation would bear any details about Mong’s mindset at the time of the collision.

“We’ll never know, I fear, whether [Mong] had fallen asleep, whether he was under the influence of something,” de Blasio said. “But it just had nothing to do with any way normal people drive,” he continued referring to surveillance video of the crash.

Queens Rep. Grace Meng said she wanted to get more details on the crash, but will work with colleagues in Washington to draft new legislation aimed at preventing similar collisions in the future.

“We might need to take a look at more stringent requirements and tightened standards to make sure that this type of accident never happens again,” said Meng, who spoke to reporters in Corona Tuesday afternoon. “I head back to Washington next week and we’re going to take a look at what standards there are especially for bus companies who have multiple infractions like this company did.”