The north-eastern US and parts of Canada were in chaos last night after a massive power cut left millions of people without electricity.

Parts of New York were left gridlocked as traffic in the city ground to a halt.

Buildings were evacuated and many people were trapped in the city's tube system.

Commentators were comparing many of the scenes to those witnessed following the 9/11 terror attacks as people queued to leave the city.

At the ferry terminal on 38th Street, in the west of Manhattan, tens of thousands of people could be seen waiting for a ferry ride back to New Jersey.

US government sources said that the power cut, which hit shortly after 9pm British time, was not linked to terrorism.

It was reported that a fire at a power plant in Manhattan had shorted a large section of the electricity grid.

New York Governor George Pataki declared a state of emergency and said officials thought the cause of the blackout was "a possible transmission problem from Canada to the US".

Michael Sheehan, deputy commissioner for terrorism in New York City's Police Department, said: "There is no evidence of any terrorism at this point.

"We've talked to Washington and there are rumours, but none of them pans out."

Power was also cut in parts of Canada, including Toronto and throughout Ontario.

In New York, areas affected stretched from Manhattan to Long Island and to the north. The buildings affected included the United Nations and New York Stock Exchange, along with Kennedy and La Guardia airports.

The Federal Aviation Authority said that flights had been stopped into six North American airports as a result of the cut.

Meanwhile, in Albany, New York, several people were trapped in lifts in Empire State Plaza, but most had been freed by 5pm (10pm British time).

People in New York queued ten deep or more at pay phones, with mobile phone service disrupted in some areas.

Every prison in New York state reported a loss of power and had switched to backup generators, said James Flateau, a spokesman for the Department of Corrections.

Thousands of people were left stranded in the streets of lower Manhattan in temperatures of 90F (32C) heat.

The cuts rivalled those in the West on August 11, 1996, when heat, sagging power lines and unusually high demand for electricity caused a huge blackout.

Four million customers were affected in nine states, one of the most severe power failures in US history.

A blackout in New York City in 1977 left about nine million people without electricity for up to 25 hours.