The financial cost of superstorm Sandy is likely to exceed $30bn (£18bn), according to economists, but is still likely to fall well beneath the $100bn of damage caused by Hurricane Katrina in 2005.

The storm caused an explosion at a power station in Manhattan which cut off power supply for nearly 200,000 houses. Power supply in some of the most badly affected areas may not be restored for a week, warned the officials.

In New York alone, over 20 serious fire incidents were reported. At least 80 houses came down during a single fire in the Breezy Point district of Queens.

New Jersey governor Chris Christie said there were houses literally floating in the middle of a coastal highway, Route 35. All the transport systems in New Jersey will take at least a week to return to regular operations.

Officials say police and troops have saved hundreds of lives, but nearly 50 people have been killed by the storm.

US President Barack Obama has declared New York and New Jersey to be major disaster areas, while New York Mayor Bloomberg said the destruction caused by Sandy "is going to be felt for quite some time. This was a devastating storm, maybe the worst that we have ever experienced."

Markets including the New York Stock Exchange are set to open after a two-day close.

Superstorm Sandy made landfall in New Jersey, wreaking havoc on states along the US east coast on the evening of 29 October.