A mysterious shiny object floating high over Manhattan's West Side set off a flurry of reports and wild speculation Wednesday that a UFO was flying over the city.

Police and the FAA said they began getting flooded with calls starting at 1:30 p.m. from people reporting a silvery object hovering high over Chelsea.

Law enforcement sources said they believed the object was likely some sort of balloon, but as of late Wednesday they had not confirmed exactly what it is.

A Daily News reporter could see a tiny, silver dot floating approximately 5,000 feet above 23th St. and Eighth Ave., where dozens of people gathered late in the afternoon to catch a glimpse.

"It's been hovering there for a while. I'm just kind of baffled," said Joseph Torres, 49, of Dyker Heights, Brooklyn, who spotted the object after leaving a movie. "How can it be ordinary? There is something going on."

Despite clear skies, it was not easy to make out the tiny object shimmering overhead.

"You really have to look up to see it," said one witness, who gave only his first name, Rico. "It's a little crazy. I guess that's why they call it an unidentified flying object because they don't know what it is."

Not long after the first sightings, messages began appearing on Twitter linking to a month-old press release announcing the publication of a book by a retired NORAD officer predicting that UFOs would buzz the earth's major cities on Oct. 13.

The Federal Aviation Administration said it received several calls to its operations center but after reviewing radar data, the agency could not find anything out of the ordinary.

"We re-ran radar to see if there was anything there that we can't account for but there is nothing in the area," said spokesman Jim Peters. "There was some helicopter traffic over the river at that time and we checked with LaGuardia Tower. And they said they had nothing going low at that time."

"Nothing that we can account for would prompt this kind of response," he said.

Peters said if it was a weather balloon or any kind of organized balloon release, authorities should have been notified in advance. Police officials said they had received no notification.

The National Security Agency declined to comment.