A city investigation into a Central Park carriage horse driver who allegedly tried to pass off an older horse with a breathing ailment as a healthy one half its age created fresh uproar Tuesday in the debate over the industry's future.

City health officials in March filed an administrative order accusing driver Frank Luo of altering a hoof ID number in order to present a 22-year-old horse as a 12-year-old one, the Associated Press reported, citing documents from a Freedom of Information request.

Dan Mathews, senior vice president of People for the Ethical Treatment of Animals, said the incident shows a ban is warranted. "These people can't be trusted," he said. "They've been singing this song and dance over the last few months, pretending they love their horses so much."

Demos Demopoulos, secretary-treasurer of Teamsters Local 553, the carriage drivers' union that opposes a ban, said of Luo: "If he's found guilty of these accusations, he said be punished to the fullest extent of the law." But Demopoulos said the probe proves that "the regulations work."

A call to Luo's company was not immediately returned. Earlier, Luo told the AP that he did not switch the horses, and claimed a city veterinarian questioned the younger horse's identity because it looks like the older one. He sold both horses to a farmer before the health department investigation was completed, though a consumer affairs department probe is continuing, AP said.

Both Mathews and Demopoulos went to City Hall Tuesday to lobby City Council members, most of whom Newsday found in a survey to be either opposed to a ban or undecided. Mayor Bill de Blasio has called for a ban, but the council has yet to introduce a bill.

PETA was accompanied by a Tulsa, Okla., couple who were visiting the city last week when they witnessed a carriage horse accident near Central Park.

Stefanie Sinclair and Rodger Curlik, 31, said a bus spooked the horse, which tried to run onto the curb, causing its carriage to flip over. The carriage pulled the horse to the ground, they said.

The carriage drivers at the scene didn't unhitch the horse and became angry when Sinclair began to take photos, she said. "Their reaction was: we don't want people knowing about this," Curlik said.

The couple shared their story with several council members, including Stephen Levin (D-Brooklyn). He called it "compelling" but said he still has to study the issue further.

Councilman Costa Constantinides (D-Queens), a ban foe, said the fallen horse -- 12-year-old Spartacus -- was treated afterward and found to be healthy.

With Matthew Chayes