UNITED NATIONS - UN chief Ban Ki-moon on Tuesday paid an emotional tribute to the 101 UN staffers who died in the devastating Haiti earthquake, the greatest single loss of life for the world body.

"Today, we commemorate the single greatest loss the UN has suffered in its history," the secretary general, choking back tears, said at a memorial service here attended by families and friends of the victims, UN staff and diplomats.

The fatalities, most of them members of the UN mission in Haiti (MINUSTAH), were among the more than 222,000 people killed when a 7.0-magnitude temblor devastated the impoverished Caribbean nation on January 12.

Some 1.2 million people were left homeless by the quake.

"We honor 101 unique paths that joined in Haiti to write the larger story of the United Nations," Ban said. "To those we have lost, let us say: we will never forget you. We will carry on your work."

The UN boss later called for a minute of silence before the names of each of the 101 victims were read out.