A plane attempting to take off at Newark airport needed to be evacuated when a possible mechanical problem caused a smoke condition, sources said.

The United Airlines flight was taxiing toward the runway and preparing to take off for Amsterdam when the brakes locked up at around 6 p.m., according to Port Authority sources.

Passengers were taken off the plane by Port Authority Air Rescue Firefighters and were shuttled back to the terminal.

A source said that the smoke may have been due to some sort of mechanical malfunction in the brakes.