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.

Sandys devastation
A damaged house is seen after Hurricane Sandy passed through in the greatly affected community of Atlantique on Fire Island, New York. Reuters
Sandys devastation
Boats are piled up after being thrown off their stands by Hurricane Sandy in a marina in Bay Shore, New York Reuters
Sandys devastation
Downtown Manhattan stood almost completely unlit after a power blackout caused by Hurricane Sandy in New York Reuters
Sandys devastation
Men pass through a flooded walkway while viewing damage caused by Hurricane Sandy on Fire Island, New York Reuters
Sandys devastation
Damage from the storm surge and wind created by Hurricane Sandy is seen in the greatly affected community of Atlantique on Fire Island, New York Reuters
Sandys devastation
Scattered debris can be seen after Hurricane Sandy passed through the heavily damaged community of Atlantique on Fire Island, New York Reuters
Sandys devastation
Cars sit under debris left from Hurricane Sandy at the Breezy Point section of Queens, New York Reuters
Sandys devastation
A view of the remains of homes devastated by fire and the effects of Hurricane Sandy at the Breezy Point section of Queens, New York Reuters
Sandys devastation
Residents use a canoe to paddle through flood waters left from Hurricane Sandy at the Breezy Point section of Queens, New York Reuters
Sandys devastation
Firefighters look at flood waters left from Hurricane Sandy at the Breezy Point section of the Queens borough in New York Reuters
Sandys devastation
Deoadato and Denino hug in front of their aunt's house destroyed by rising waters from last night's storm surge due to Hurricane Sandy in New York Reuters
Sandys devastation
New Jersey Army National Guard aerial views shows the damage caused by Hurricane Sandy to the New Jersey coast Reuters
Sandys devastation
Kevin Sousa enlists the help of neighborhood kids to unroll a carpet that was soaked after their house was flooded as a result of a storm surge caused by Hurricane Sandy in Newport Reuters
Sandys devastation
A car destroyed by flooding sits at the entrance of the Con Edison Substation in Manhattan after the storms from last night's Hurricane Sandy in New York Reuters
Sandys devastation
Workers clean up leaves outside the Con Edison Power Plant which was severely damaged in storms from last night's Hurricane Sandy in New York Reuters
Barack Obama Storm New York