Hundreds of New York City homes deemed to be safety hazards after superstorm Sandy will be razed in a vast operation the office of Mayor Michael Bloomberg describes as "unprecedented."

Some 200 homes in the New York boroughs of Queens, Brooklyn and Staten Island that were hardest hit by Sandy will be demolished in the coming weeks or months, the office said.

"We've never had this scale before," the director of the city's buildings department, Robert LiMandri, said in an interview with the New York Times published Sunday.

"This is what New Yorkers have read about in many other places and have never seen, so it is definitely unprecedented."

New York is still picking up after last month's mammoth confluence of a hurricane and a seasonal "nor'easter" storm plowed through the US northeast, landing a direct blow on the city and parts of neighboring New Jersey.

On Sunday, Vice President Joe Biden visited New Jersey, overflying areas like devastated Seaside Heights, a well-known beach town.

"We have an awful lot of work to do," Biden said.

"This is a national responsibility," he said. "This is not a local responsibility."

The storm disrupted deliveries and power at fuel stations across New Jersey and New York, forcing Bloomberg's office to announce Sunday that gasoline rationing put in place on November 9 would continue through Friday.

The rationing so far has "worked well and helped to reduce wait times and lines at the pump," Bloomberg said in a statement.

He said it would remain in place until Friday "to ensure we do not risk going back to the extreme lines we saw prior to the system being implemented."

The rationing system allows motorists to pump gas at area service stations on alternate days, depending on whether their license plates end in an even or odd number.

Bloomberg emphasized that nearly one-third of gas stations are still closed, which could become a problem as many drive to visit relatives for the Thanksgiving holiday Thursday.

The New York homes set to be razed will be in addition to the 200 or so that were already to be bulldozed after being heavily damaged by wind, water or by storm-sparked fire.

New York City's Buildings Department must still issue a ruling on another 500 damaged structures, some of which could also meet the same fate, LiMandri said.

A decision on how to rebuild these devastated neighborhoods has become another subject of intense debate.

Most of the homes that will be torn down are modest single- or two-family houses which, in some instances, have been passed down from generation to generation.

Some that were expanded and renovated over the years could not be rebuilt as they were because they would fail current building codes.

Moreover, many families fled ahead of the storm, and authorities have had trouble locating them to discuss plans for their battered homes.

"This is not easy, in this case, because of all these displaced people... we're going to do the best we can, but we may have to move on it if we can't find them," LiMandri told The Times.