Foreign diplomats who are in Iran for a two-day tour of the country's nuclear sites have headed to the city of Arak to visit the heavy water reactor there,Press TV reported.
Representatives from the International Atomic Energy Agency (IAEA), the Non-aligned Movement (NAM), Group of 77 and the Arab League are among the visitors.
Iran extended the invitation to allow the inspection of its nuclear facilities as a goodwill gesture aimed at displaying the "transparency" of its nuclear program in the spirit of international cooperation.
The delegates, who represent more than 120 countries, arrived in the Iranian capital early Saturday.
Iran invited EU member states as well but they refused Tehran's offer.
Iran's Ambassador to the IAEA Ali Asghar Soltanieh said the EU lost the "historic opportunity" for further cooperation with Iran and visiting the country's peaceful nuclear activities, IRNA reported.
According to Soltanieh, this is not the first time that foreign delegates visit Iran's nuclear sites.
He said that representatives from the NAM and Group of 77 visited Isfahan UCF nuclear site in 2007.
Earlier on Friday, Iranian caretaker Foreign Minister Ali Akbar Salehi announced that the Islamic Republic is ready to take any measure to help build confidence in its nuclear program but will not compromise on its legitimate rights.
"We are ready to take any measure in line with building mutual confidence with the West while protecting our nuclear rights," he said.
Salehi, who is also the director of the Atomic Energy Organization of Iran, expressed hope that the country's goodwill gestures would help build confidence.
"There is no country in the world that is ready to expose its nuclear facilities, and this (invitation) demonstrates the peaceful nature of Iran's nuclear activities," Salehi stated.