VIENNA, Austria - Iran has turned away UN inspectors wanting to examine its underground nuclear site in an apparent violation of the Nonproliferation Treaty, diplomats and UN officials said Monday.

Iranian Foreign Minister Manouchehr Mottaki listens during the South Africa-Iran Joint Bilateral Commission at the Presidential Guesthouse in Pretoria, South Africa, Monday, Aug. 21, 2006. Iran has finished considering an offer to settle its international nuclear dispute, Mottaki said in Pretoria on Monday. [AP]

The officials, who spoke on condition of anonymity because of the confidentiality of the information, told The Associated Press that Iran's unprecedented refusal to allow access to the facility at Natanz could seriously hamper international efforts to ensure that Tehran is not trying to make nuclear weapons.

The revelation came on the eve of Iran's self-imposed Aug. 22 deadline to respond to a Western incentives package for it to roll back its disputed nuclear program. The

United Nations has given Tehran until the end of August to suspend uranium enrichment.