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Calls to New York City’s emergency dispatch centers have hit levels not seen since the terror attacks on Sept. 11, 2001, as the city deals with the coronavirus outbreak, according to an emergency workers’ union.

Medical calls are up to around 6,500 calls per day — hundreds more than the city’s busiest day of the year, New Years Day when around 5,000 calls come in, a spokesman for Local 2507 confirmed.

The surge is delaying ambulances by three or four hours in some cases, according to the spokesman.

Calls for coronavirus-like symptoms have jumped from around 20 a day three weeks ago to 300 last week — and that number continues to grow, the spokesman said.

The 40 percent uptick in daily calls for medical aid has stretched the 2,000 dispatchers thin with around 200 dispatchers out sick. The NYPD, FDNY and EMS staff the 911 call centers.

Union head Oren Barzilay, told Bloomberg, which first reported the call numbers, if 10 percent more dispatchers call out sick, “I think the city is going to being a crisis.” [sic]

The NYPD and FDNY have not provided data on medical calls.