Austria ? The United States and key allies are pressing the U.N. nuclear monitoring agency to find Iran in violation of its commitments to the Nuclear Nonproliferation Treaty for Tehran’s refusal to allow remote monitoring of its underground uranium enrichment plant, diplomats said Thursday.

The International Atomic Energy Agency has itself increased the pressure on Iran, the diplomats said.

The diplomats said a senior IAEA official recently told the Iranians to accept an agency request for additional cameras at the Natanz enrichment site by the end of this week.

At issue is Tehran’s refusal to allow the agency comprehensive monitoring of its expanding enrichment program at Natanz, where it has linked up hundreds of centrifuges meant to produce material that can be used to generate nuclear energy – or produce the fissile core of nuclear warheads.