The United Nations says Iran has refused to allow nuclear inspectors to revisit a suspect military site.

In a report to the International Atomic Energy Agency Friday in Vienna, inspectors say Iran recently refused to grant them access to its Parchin military base, where Washington says Tehran is simulating atomic weapons tests.

Deputy Director General for Safeguards Pierre Goldschmidt said Iranian officials claimed the previous visit in January had fulfilled inspectors' demands.

He said the country also had delayed reporting an extensive tunnel system under construction beneath a uranium conversion plant in the central city of Isfahan.

Mr. Goldschmidt also said Iran continues to build a heavy water reactor which can produce plutonium, despite requests to cease construction.

Iran's representative at the IAEA meeting said Tehran intends to keep producing nuclear fuel for peaceful purposes.