Representatives from the U.N.'s nuclear watchdog agency and Iran hit an impasse Friday in talks attempting to resolve possible access to a military site that is key to Iran's controversial nuclear program.

The International Atomic Energy Agency's chief inspector, Herman Nackaerts, told journalists in Vienna Friday the talks were “disappointing” and provided “no progress.”

He added that Iran's envoy to the IAEA and agency officials did not set a date for another meeting.

The agency's new round of talks with Iran was started in an effort to negotiate a deal that would allow the agency to resume an investigation into suspected nuclear weapons research in the Islamic state.

The IAEA wants access to Iran's Parchin military base, where the agency believes Iran has been conducting atomic weapons research. Tehran says Parchin is a conventional weapons facility and insists the Iranian nuclear program is peaceful.

Both sides say progress has been made in previous discussions on the issue this year, although differences remain.

Meanwhile, Chinese President Hu Jintao met with his Iranian counterpart Mahmoud Ahmedinejad in Beijing Friday. Chinese state media report that the Chinese leader urged the Iranian leader to take a flexible and pragmatic approach in the IAEA talks.

A U.S. research organization obtained satellite images last month that indicated Iran may have attempted to destroy traces of nuclear weapons testing at Parchin.