UN inspectors did not visit any of Iran's nuclear sites during their visit to the country this week, reports say.
Instead they concentrated on talks with officials.
An Iranain official told the news agency IRNA that the experts from the International Atomic Energy Agency conducted negotiations with Iranians and did not visit the sites where uranium is being enriched.
He said the talks were held in a "positive and constructive atmosphere."
There was no comment from the UN team.
Tension has been building over Iran's nuclear programme. The US and its allies charge that Iran is using its uranium enrichment facilities to produce material for nuclear weapons.
Iran has declined to abandon its enrichment labs, saying it seeks to operate the reactors only for energy and medical purposes, not for making weapons.
The IAEA team arrived on Sunday on a visit set for three days.
Mohammad Karamirad, a member of the influential parliamentary committee on national security and foreign policy, said the visit showed Iran has had "comprehensive and honest co-operation with the agency".
Mr Karamirad said: "The visit can be the beginning of a new round of talks with the West, and it proves the peacefulness of Iran's nuclear activities."