Iran says allegations by the International Atomic Energy Agency that Tehran is withholding details on its sensitive nuclear activities are based on fake evidence.
Iran's envoy to the IAEA, Ali Asghar Soltanieh, made those remarks Thursday to the U.N. agency's 35-nation board in Vienna.
An IAEA report released last month said Iran has provided insufficient evidence to refute Western accusations it is trying to make nuclear weapons.
Earlier this week, IAEA chief Mohamed ElBaradei said Iran must provide "full disclosure" about past activities suspected to have been part of a nuclear weapons program.
Meanwhile, diplomats say Syria will only allow IAEA inspectors to visit the al-Kibar site in the Syrian desert that the United States alleges was once a nuclear facility and not three other suspected sites.
The remote desert facility was destroyed in an Israeli air raid last September.
The diplomats say Syrian nuclear official, Ibrahim Othman told the IAEA board in Vienna today the inspectors could visit the site during a trip to Syria June 22-24.
They say Damascus rejected IAEA interest in visiting the other sites.
The United States has warned Syria not to hinder an IAEA probe into allegations that Damascus has been pursuing clandestine nuclear activities.
The U.S. ambassador to the IAEA, Gregory Schulte, told media outlets Wednesday that Syria must give the United Nations agency open access to any suspected nuclear site it asks to inspect.
Some information for this report was provided by AFP, AP and Reuters.