NEW YORK – International arms control inspectors say sensitive equipment that could be used to extract plutonium for an atomic bomb is missing from a Tehran laboratory months after the apparatus was disclosed to a United Nations watchdog agency.

The report is expected to feed suspicions in the West that Iran is attempting to hide the nature and scope of its nuclear program.

Iran agreed in May to allow inspectors greater surveillance and access to the area where it is producing 20 percent enriched uranium meant for a Tehran medical reactor, clearing up one of the points of contention between the Islamic republic and the International Atomic Energy Agency.

Still, analysts and diplomats say overall cooperation between Iran and the agency continues to deteriorate, a dynamic that emerged after the tenure of new IAEA Secretary-General Yukiya Amano began late last year.

“If Iran were really interested in cooperation with the agency, it would have allowed the IAEA to undertake additional surveillance measures before it started enriching up to 20 percent,” said a Western diplomat in Vienna, speaking on condition of anonymity.

Iran’s nuclear program has been a major point of contention with the West and Israel, which suspect Iran of putting together the infrastructure to eventually build an atomic bomb. Tehran insists its nuclear program is meant for civilian purposes only, and it accuses the West of trying to deny Iranians their rights and national aspirations.

IAEA inspectors were told in January by a scientist or official at Tehran’s Jabr Ibn Hayan Multipurpose Research Laboratory that Iran was conducting pyro-processing experiments, work potentially consistent with creating warheads that could be used in developing a nuclear weapon.

But during an April 14 inspection of the lab, the equipment — used to remove impurities from uranium metal — had been removed, said the agency’s report to its board of governors ahead of a meeting next week. Iran had earlier backtracked, insisting to inspectors it was not engaged in pyro-processing work.

“It will bring Iran close to being able to separate plutonium and thus have a second path to a nuclear weapon,” said Mark Fitzpatrick, an analyst for the International Institute for Strategic Studies in London.

“Given the evidence of military connections to Iran’s nuclear program, it is worth asking the purpose for which Iran is studying the production of uranium metal.”