Jan. 8 (Bloomberg) -- New York City officials are looking for the origin of a noxious smell that engulfed parts of Manhattan and New Jersey this morning, sickening at least 27 people.

Mayor Michael Bloomberg said a ``small gas leak'' was reported in the downtown Greenwich Village neighborhood. Later, Consolidated Edison Inc. spokesman Chris Ohlert denied any leak in the utility's system.

Mayoral spokesman Stu Loeser said the mayor was acting on information City Hall had at the time and now ``wasn't disputing'' ConEd's account.

New York Emergency Management Director Joseph Bruno said 27 people had called emergency services reporting that they were ``feeling ill from the smell,'' which was reported from Battery Park in Lower Manhattan to Midtown.

By mid-afternoon, most of the inquiry was focused on New Jersey, and there were no additional complaints from Manhattan, said Jarrod Bernstein, spokesman for the agency.

Bloomberg, in his morning press conference, said there was no known health threat from the smell. The city's many air sensors ``do not show any high concentrations of natural gas that would give us cause to be concerned,'' he said.

``This is what we know: The smell is there, we don't know the source of it, it does not appear to be dangerous and some of the facilities that were shut down are now being reopened,'' Bloomberg said.

The odor was also detected in Jersey City, New Jersey. Maria Pignataro, spokeswoman for Jersey City Mayor Jerramiah Healy, said there was a strong smell when she left for work in the morning, and it later dissipated.

PATH commuter train service into Manhattan from Hoboken and Newark, New Jersey, was restored as of 10:30 a.m., Steve Coleman, a spokesman for the Port Authority of New York and New Jersey, said. Two commuter lines from New Jersey into Manhattan were suspended earlier because of the investigation.

Bloomberg said the smell resembled mercaptan, a sulphur- based chemical compounded added to natural gas.

Natural gas and propane are naturally colorless and odorless. Mercaptan gives the gasses the distinctive smell of rotting vegetables that can be detected in case of gas leaks. In natural gas, mercaptan is injected directly into distribution pipes. Only very small quantities of the potent gas are required.

The mayor is founder and majority owner of Bloomberg News parent Bloomberg LP.

To contact the reporter on this story: Todd Zeranski in New York at tzeranski@bloomberg.net; or Henry Goldman in New York at hgoldman@bloomberg.net.

Last Updated: January 8, 2007 14:55 EST