Iran and the U.N. nuclear agency have begun their second day of talks in Vienna, with Iran's envoy saying the discussions so far have been “good.”

Before going into Tuesday's meeting with negotiators from the International Atomic Energy Agency, Iran's Ali Asghar Soltanieh told reporters the atmosphere of the talks had been “very constructive.”

On Monday, the U.N. nuclear agency again urged Iran to give it access to the sites, people and documents it seeks as part of its probe into whether Tehran is trying to develop nuclear weapons.

Iran has so far denied the IAEA access to the Parchin military site near Tehran. Officials suspect Iran has built a container there that could house nuclear explosives tests, and Western diplomats accuse Tehran of trying to remove incriminating evidence before allowing U.N. inspectors inside the facility.

Iran has dismissed the allegations as being “childish” and “ridiculous.”

The five permanent members of the U.N. Security Council plus Germany are following the Vienna meeting closely ahead of their talks next week with Iranian officials in Baghdad. The so-called P5+1 countries – in addition to Germany, the United States, Britain, France, Russia and China – are seeking to assess the possible military capability of Iran's nuclear sites.

Western powers have long suspected Iran of seeking to develop nuclear weapons under the cover of a civilian energy program. Tehran denies the allegations.