Damage wreaked on the Statue of Liberty by Hurricane Sandy has yet to be fully repaired, and it remains unclear when the New York icon will again welcome tourists from around the world.

"We do not have a reopening timeline yet," said spokeswoman Linda Friar of the National Park Service, the US government agency that oversees the statue and the small island in New York harbor on which it stands.

"There is still a lot of work yet to be done," she told AFP.

"Power and communications systems need to be restored (and) docks and walkways around Liberty Island island must also be repaired. These are very large infrastructure projects."

Hurricane Sandy dealt New York a powerful blow when it swept up the northeastern US coast on October 29, lifting sea levels by nearly 15 feet (4.2 meters) at the southern tip of Manhattan.

Liberty Island, just 10 acres (four hectares) big, was three-quarters flooded -- in some places by more than five feet (1.5 meters) of water -- and the two docks on which tourists arrive by small ferry boats were swept away.

The statue itself, which stands 93 meters high and weighs more than 200 tons, sustained no damage. Ironically, the viewing platform within its crown had reopened to the public on the eve of the storm, after a year of repairs.

In mid-December, after an on-site visit, Interior Secretary Ken Salazar estimated the cost of repairs for Liberty Island and nearby Ellis Island at $59 million.

"We're going to get this done as soon as we possibly can because (the Statue of Liberty) is such an important icon for New York and America," Salazar told reporters.

Gateway to the United States for millions of European immigrants from 1892 to 1924, Ellis Island -- itself a much-visited museum -- also remains closed for the foreseeable future.

Friar said that, in Hurricane Sandy's wake, staff and emergency crews have cleared away debris, removed and stabilized docks, fixed safety hazards and undertaken steps to prevent mold from spreading.

Some historic items and documents from Ellis Island have meanwhile been transferred to Maryland for safekeeping.

The senior US senator for New York state, Charles Schumer, a Democrat and native New Yorker with a reputation for focusing on local issues such as tourism, expressed outrage last month over the lack of a reopening date.

"Tourists, businesses and all New Yorkers need to know that the end is in sight," he said. "As an enduring symbol of our nation and our city, Lady Liberty cannot be allowed to languish any longer than necessary."

The Statue of Liberty typically attracts four million visitors a year, generating millions of dollars of revenue.

Its closure prompted a loss of employment for around 400 people, from security officers and ferry boat crews to souvenir hawkers and other small entrepreneurs, Schumer said.

The National Park Service meanwhile reassigned 29 guides to other locations in the New York and New Jersey area.

France gave the Statue of Liberty to the United States -- a decade late -- to mark the centennial of the July 4, 1776 Declaration of Independence.

It was conceived by French sculptor Auguste Bartholdi, with Gustave Eiffel -- the engineering mastermind behind the Parisian tower that bears his name -- in charge of its internal structure.

Since 1984 its has been listed as a world heritage site by UNESCO, the United Nations cultural agency.