Banksy's final piece appeared attached to the side of a vacant building at the corner of 35th Street and Borden Avenue in Long Island City, near the Long Island Expressway. View Full Caption Instagram/banksyny

LONG ISLAND CITY — It's enough to leave Banksy deflated.

The fate of the balloons left by the prolific British street artist in Queens last week is up in the air, because the NYPD — which confiscated the items as arrest evidence — didn't invoice them as art.

Deputy Chief Jack J. Trabitz, the commanding officer of the NYPD's property clerk division, told the New York Times that the inflatable letters were categorized by police as "balloons," and not art.

That means they could be discarded unless the department ultimately deems them valuable — or someone comes forward to claim them, the paper reports and DNAinfo confirmed.

The balloons, which spell out "Banksy!" were discovered last Thursday attached to a warehouse in Long Island City and were hauled off by police when a scuffle broke out after would-be thieves climbed the building and tried to take them.

Three men were arrested for trespassing at the scene, police said.

The balloons were confiscated and vouchered by the NYPD, according to a spokesman who said it is the responsibility of the owner to claim them. For property determined to be arrest evidence, the owner must get a release from the appropriate District Attorney's office, the spokesman said.

A gallery owner who specializes in Banksy's work told the Times that the inflatable letters could be worth between $200,000 and $300,000.

The balloons were the final installment in Banksy's month-long New York City residency, "Better Out Than In," in which the artist left his works scattered across the five boroughs.