International Atomic Energy Agency (IAEA) investigators have begun a new round of talks with Iran in Tehran.
The January 16 visit by the IAEA is part of a probe into Iran's nuclear research, which the West suspects is aimed at developing atomic weapons.
Investigators also hope to secure access to Parchin, a military site near Tehran the IAEA suspects was used to test key nuclear weapons parts.
Iran's ISNA news agency provided no details on the outcome of the first day of talks at Iran's Atomic Energy Organization headquarters in Tehran, but said they would continue on January 17.
The visit comes as Iranian media reported that Tehran and six world powers had agreed on the next round of their negotiations.
The reports said they would take place on January 28-29.
ISNA reported no agreement had been reached on a location for the talks.
Based on reporting by AP and Reuters