The head of the United Nations' nuclear agency, Mohamed ElBaradei, says Iran has agreed to let UN inspectors back into the country later this month.
Mohammed ElBaradei said Iran had given a new date for inspections
Iran banned IAEA inspectors after the agency issued a resolution accusing Tehran of secret nuclear activities.
But IAEA chief Mohamed ElBaradei said Tehran had told him the "new date for inspectors arriving [was] March 27."
Iran, which says its nuclear activities are for peaceful purposes, called the halting of visits a technical problem.
Mr ElBaradei said the delay was regrettable, but he said the inspections were still on schedule.
Hassan Rowhani, secretary general of Iran's Supreme National Security Council, urged the International Atomic Energy Agency board to "bring a closure to Iran's case".
Mr Rowhani said that resolving the problems with the IAEA was "not very complicated".
The United States has accused Iran of developing a secret weapons programme and wants the International Atomic Energy Agency to declare the country in breach of the Nuclear Non-proliferation Treaty (NPT).
On Sunday, Mr ElBaradei said the IAEA hoped to end its investigation of Iran's nuclear programme by the end of this year if no evidence was found that Tehran worked on the development of nuclear weapons.
"If there's no smoking gun, if there's no 800-pound gorilla ... I see no reason why we should not be able to have at least most of it wrapped up by the end of the year," he said.
Mr ElBaradei said allowing UN inspectors to return quickly would help dispel suspicions that Tehran had something to hide.
Iran imposed a freeze on inspections in retaliation to an IAEA's resolution on Saturday "deploring" Iran's failure to report some nuclear activities.
The IAEA censured Iran for omitting key atomic technology from an October declaration, although it tempered the criticism with praise for Tehran's increased nuclear openness.
The watchdog has a June deadline to present a judgment on Iran's nuclear activities.