One worker is fighting for life and another being rescued from the Hudson River after an explosion on a barge.

The barge blew up at the North River Wastewater Treatment Plant near West 138th Street in New York City about 10.30am on Saturday.

The small explosion was reportedly caused by methane igniting in a 'malfunction' of the vessel, but it did not start a fire.

One of the workers, who was on the barge during the explosion, is in critical condition, according to authorities.

Helicopters were seen hovering over the barge and rescue boats rushed to the area to rescue the man overboard, who was pinned between the boat and the dock.