Debris is seen at Jacob Riis Park in the Rockaways section of the Queens borough of New York. City officials say an unprecedented operation to bulldoze unsafe, storm-damaged homes is under way.

New York - An estimated 200 houses severely damaged by superstorm Sandy in New York City are beyond repair and must be completely torn down, the city's buildings department said.

Most of the houses are one- or two-family homes in Queens and Brooklyn and on Staten Island, The New York Times reported on Monday. They are in addition to 200 houses that were already completely destroyed by wind, water or fire when Sandy struck three weeks ago.

“We've never had this scale before,” said Robert L. LiMandri, director of the buildings department. “This is what New Yorkers have read about in many other places and have never seen, so it is definitely unprecedented.”

About 2 100 customers in New York were still without electricity early on Monday, the US Department of Energy said on its website. That's down from a peak of more than eight million.

Mayor Michael Bloomberg extended petrol rationing until Friday, and Vice-President Joe Biden visited New Jersey on Sunday, saying rebuilding the region was a “national responsibility”. The storm killed more than 100 people in the United States.

The storm also resulted in a surprising discovery on Fire Island - a shipwreck from the early 20th century, Time magazine reported. Experts are speculating that the wreck could be the Bessie White, which sank off the island in thick fog.

The four-masted schooner was discovered along the Fire Island National Seashore, a recreation area. Parts of the ship have poked through the sand before, but it is now more dramatically exposed than ever before, a park official said. The ship was loaded with coal when it sank. All crew members survived. - Sapa-dpa