Senior inspectors from the International Atomic Energy Agency (IAEA) and Iranian officials have ended two days of talks in Tehran with no sign of a breakthrough.
Iran's ISNA and Fars news agencies said a further meeting between the IAEA and Iran would be held on February 12 in the Iranian capital, but gave no details.
There has been no confirmation of a planned meeting from the IAEA.
Diplomats said the UN team was due to return to Vienna on January 18.
The IAEA is probing whether Iran is trying to develop nuclear weapons.
The IAEA is also seeking access to the Parchin military complex, where the agency believes Iran has conducted explosives test with possible nuclear applications.
Iran denies Western accusations it is seeking atomic weapons.
Based on reporting by Reuters and AFP