Animal welfare activists joined with parks advocates Thursday to denounce as a “backroom deal” a compromise floated by Mayor Bill de Blasio to limit the horse-drawn carriage industry to the confines of Central Park.

Members of Friends of Animals and the Coalition to Ban Horse-Drawn Carriages at a City Hall news conference said they will continue to push for a full ban rather than the proposed reduction to 75 from 180 working horses.

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“That’s what Mayor de Blasio promised,” Edita Birnkrant of Friends of Animals said of a ban. Other animal rights groups have endorsed the plan.

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Geoffrey Croft of NYC Park Advocates said that using public park space for a private enterprise could be grounds for a lawsuit.

The City Council transportation committee will hold a hearing Friday morning on the bill, an “agreement in concept” between de Blasio, Speaker Melissa Mark-Viverito and the Teamsters union representing the carriage drivers.