The U.N. atomic agency believes nuclear material that Iraq said had been seized by insurgents was "low-grade" and did not pose a significant security risk.

Iraq told the United Nations in a July 8 letter seen by reporters on Thursday that "terrorist groups" had seized nuclear materials used for scientific research at a university in the north. It appealed for help to "stave off the threat of their use by terrorists in Iraq or abroad."

The International Atomic Energy Agency "is aware of the notification from Iraq and is in contact to seek further details," IAEA spokeswoman Gill Tudor said. "On the basis of the initial information, we believe the material involved is low-grade and would not present a significant safety, security or nuclear proliferation risk. Nevertheless, any loss of regulatory control over nuclear and other radioactive materials is a cause for concern."

Iraq's U.N. ambassador, Mohamed Ali Alhakim, told U.N. Secretary-General Ban Ki-moon in the letter that nearly 40 kilograms (88 pounds) of uranium compounds was kept at Mosul University.

"Terrorist groups have seized control of nuclear material at the sites that came out of the control of the state," Alhakim wrote, adding that such materials "can be used in manufacturing weapons of mass destruction."