The indicted former chief of Enron, Jeff Skilling, was taken to hospital on Friday after accusing patrons at a bar of being FBI agents and trying to frisk them for recording devices, police officials said.
Police picked up Skilling at 4 am EDT (0800 GMT) in Manhattan's Upper East Side, said Det. Thomas Kuchma.
"He was acting erratically, taken into custody and then removed to a New York hospital for evaluation because of his erratic behaviour," said detective Kuchma, who declined to give more details.
The police did not press charges against Skilling and officials at New York Presbyterian Hospital - where police sources said Skilling was sent for observation - said they had no information on him.
Media reports said the hospital released Skilling about six hours after his arrival.
Emergency medical personnel, who were present when Skilling was picked up, reported that he was highly uncooperative, police sources told Reuters.
Skilling, 50, is the highest-ranking former executive charged in the fall of former energy trading powerhouse Enron. The ensuing scandal rocked Wall Street and Washington, sparking a wide-ranging probe of corruption in corporate America.
On February 18 he was charged with 35 counts of conspiracy, fraud, insider trading and lying about Enron's finances. Skilling's lawyer disputed the police reports.
"Mr Skilling and his wife were in New York attending a concert for one of his children, when two strange men began aggressively questioning him about Enron," Daniel Petrocelli, Skilling's lead counsel, told Reuters.
A floor manager at Vudu, a trendy Upper East Side club that was among the places Skilling had reportedly visited, said he had received complaints early Friday morning from some patrons that three men were causing a disturbance at the bar.
"I went up to them and asked if everything was OK, and looked at (Skilling) in the eye, and he said they were OK," said Chris Oprysk, 26, who is in charge of club security.
Skilling was dressed in jeans, a button-down shirt and sports jacket, while his two male companions were dressed more casually, Oprysk said.
Skilling, who has pleaded not guilty to the charges against him, resigned as Enron's CEO in 2001 after just six months in the job and months before its collapse.