New York City's fiscal watchdog said the city faces much bigger budget deficits in coming years than the mayor has forecast and warned state lawmakers about treating the city like a "piggy bank."

The state, like the city, is finalizing its budget and will soon make decisions affecting New York City.

"Some upstate legislators just don't get it," New York City Comptroller Scott Stringer said during his review of the city budget on Wednesday. "They see New York City as their piggy bank."

Stringer cautioned against last-minute, late-night budget decisions that could deprive the city of resources. His comments reflected growing frustration with state lawmakers over their suggestions that the city is flush with cash after a stronger economic recovery than other parts of the state.

New York State Governor Andrew Cuomo has had a tense relationship with New York City Mayor Bill de Blasio, persuading his fellow Democrat last year to pay $2.5 billion toward the city's public transportation system, which is run by the Metropolitan Transportation Authority, a state agency.

There have also been suggestions in the state capital that the city could do more to fund healthcare costs and pay more for the city's university system.

New York State legislators are known for "vampire" budget sessions that go into the early hours to beat the budget deadline at the start of the state's fiscal year on April 1.

Stringer said that although next year's budget remained balanced, the total gaps forecast through fiscal year 2020 are $1 billion more than the mayor's office had predicted.

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"Budget monitors and rating agencies have all applauded this administration's fiscal prudence and focus on protecting against economic uncertainty – and investors agree," said Amy Spitalnick, a spokesperson for de Blasio.

The mayor's office points out that Stringer projects $900 million in additional tax revenue for this financial year and next, and cites that as an example of cautious revenue projections on the city's part.

Stringer said the mayor should not have included $731 million from the sale of taxi medallions through 2020, saying the taxi business is currently in upheaval.

The city has already cut it expectations for revenue from taxi medallion sales but Stringer has been more aggressive in elimintaing it from later years.

He also said some taxes would be lower than the mayor is predicting and that costs for overtime, healthcare and homeless shelters would be higher.