The International Atomic Energy Agency visit to Iran has fallen through after the UN-mandated inspectors were barred from entering a nuclear research facility on Tuesday, the BBC reports.
A statement from the IAEA said that no headway had been made in clarifying allegations that Iran has been researching nuclear weapons. The inspectors' two-day visit, their second in three weeks, was called off after "intensive efforts" yielded no cooperation from the Iranian government.
A major sticking point in deliberations was access to a nuclear research site in Parchin which has aroused suspicion of weapons research and gained attention and threats of violence from Israel.
The Iranian government has repeatedly denied allegations that it has been developing nuclear weapons, claiming that its nuclear research is focused squarely on energy uses.
"The Islamic Republic of Iran, with a thoughtful, jurisprudent, theoretical approach, believes that owning a nuclear weapon is a big sin," said supreme Iranian leader Ayatollah Ali Khamenei, according to the Washington Post. "It also believes that keeping such a weapon is vain, harmful and dangerous."