A Madrid-bound Delta Air Lines plane returned to New York early this morning after suspicious wires were found in a bathroom, but no explosives were discovered.

Delta Flight 126, a Boeing 767-300 with 206 passengers onboard, landed safely at John F Kennedy Airport about 90 minutes after takeoff.

The aircraft was examined by bomb technicians and no explosives were found.

Delta described the situation as a "security concern".

Police spokesman Paul Browne said two wires inside of small, plastic straws were found in a bathroom, one in the sink and one in the toilet.

It is not clear whether a flight attendant or an air marshal made the discovery. Nor was it clear where the wires came from.

They were not part of the smoke detector in the bathroom, Mr Browne said.

Once back in New York, Mr Browne said the aircraft was examined by bomb technicians and no explosives were found.

Two passengers were questioned but neither was held.

One was a woman from Argentina who reported trouble breathing around the time of the discovery.

Also interviewed was a man believed to be the last person to use the bathroom before the wires were found. He denied any knowledge of the wires.