Iran claims information allegedly leaked from the UN nuclear monitoring agency, the International Atomic Energy Agency, was used in the killing of one of its nuclear scientists last week.
Mostafa Ahmadi Roshan was killed in Tehran on January 11 after a magnetic bomb clinging to the door of his car exploded.
Iran's Deputy UN ambassador, Eshagh Al Habib, said there was a "high suspicion" that information "obtained from United Nations bodies" had been used to plan the assassination.
"There is a high suspicions, that these terrorists circles used the intelligence obtained from United Nations bodies, including the sanctions list of the Security Council and interviews carried out by IAEA (International Atomic Energy Agency) with our nuclear scientists to identify and carry out their malicious acts," Al Habib said at UN headquarters in New York.
UN spokesman Martin Nesirky said he was looking into the allegations.
Iran has blamed the United States and Israel for the killing.
Both countries deny any role in the attack and Washington has condemned it.
Iran is at odds with Western governments over its nuclear program and denies it is trying to build nuclear weapons.
Tehran has faced four rounds of UN sanctions for failing to halt uranium enrichment.
compiled from agency reports