UNITED NATIONS – The United Nations headquarters suffered severe damage when Sandy, a massive storm that hit the U.S. East Coast this week, caused heavy flooding at the world body’s Manhattan complex along the East River, the U.N. security chief said on Thursday.

Sandy made landfall in New York City on Monday evening, flooding many parts of lower Manhattan and leaving nearly 2 million residents of New York state without electricity. The storm surge from the East River also affected the United Nations, which remained shut from Monday to Wednesday.

“Tuesday morning it became evident that we had suffered pretty major damage in the United Nations,” U.N. Under-Secretary-General for Safety and Security Gregory Starr told reporters.

“The storm surge, which was higher than anyone predicted, came over the FDR Drive, came into the service drive at the 3B (basement) level of the United Nations, rose above our loading dock levels of the 3B and then started plummeting down into the lower levels of the United Nations,” he said.

Starr said this caused problems with the U.N. complex’s chilled-air plant, electrical operations and communications.

“We are not back to full operations,” he said. “We clearly have some damage to our communications systems.”

Susana Malcorra, U.N. Secretary-General Ban Ki-moon’s chief of staff, said U.N. peacekeeping, humanitarian and other operations worldwide were not affected by the impact Sandy has had on United Nations headquarters in New York City.

U.N. officials told reporters that they expected U.N. websites to be operational on Thursday and some were already functional. Many U.N. websites have been out of operation since Monday.

U.N. Under-Secretary-General for Management Yukio Takasu said the entrance to the U.N. General Assembly hall was damaged, as was a plastic temporary rain cover over the assembly hall.

“Core infrastructure of all buildings in headquarters is assessed as being intact,” Takasu said. “I think this is good news.” He added that no U.N. employees had been injured.

SMALL FIRE BROKE OUT DURING SANDY

Takasu gave no estimates for the cost of the damage caused by Sandy, though he said the chilled-air plant was insured and negotiations with the insurers had begun.

“Most serious damage is due to flooding,” Takasu said.

Starr said the U.N. printing shop was also badly hit by flooding, though there was no damage to archival documents at the United Nations, which stores originals copies of hundreds of international treaties.

A small fire broke out in the electrical switchboard area when it flooded during the storm, Takasu said, which led to a decision to temporarily cut off all electricity to the United Nations complex.

The United Nations reopened for business on Thursday, though it was unclear when all the damage would be repaired and clean-up operations completed.

Due to flood damage, the U.N. Security Council relocated from its normal chambers to a temporary building inside the U.N. campus on Wednesday to hold a meeting on Somalia.

Takasu said the U.N. would have to reassess the placement of sensitive equipment like air chillers and switchboards in the basement areas. The decision to locate them in the lower levels of the more than 60-year-old U.N. building had been based on analysis of weather patterns going back to the 19th century.

“This was a very unprecedented hurricane,” Takasu said, adding that the U.N. management might consider relocating certain infrastructure after conducting a “lessons learned” assessment of the impact of Sandy had on the United Nations.

Michael Adlerstein, who heads a $1.9 billion renovation of the United Nations due to be completed in 2013, said Sandy would not delay the completion of his overhaul of the U.N. complex.

(Editing by Stacey Joyce)