The head of the UN nuclear agency (IAEA) is visiting Tehran on July 1 as nuclear negotiations between Iran and six major powers were extended for another week.
Yukiya Amano will meet President Hassan Rohani and other senior Iranian officials, the IAEA said in a statement.
Amano hopes "to accelerate the resolution of all outstanding issues related to Iran’s nuclear program, including clarification of possible military dimensions," the statement said.
Iran's Mehr news agency said Amano will "receive Iran's alternative proposal to nuclear scientists' questioning."
Iran and the six powers -- Britain, China, France, Germany, Russia, and the United States – have given themselves until July 7 to reach a comprehensive nuclear agreement.
The decision was announced on June 30 as a midnight deadline approached in talks in Vienna without a deal.
Negotiators are working to strike an agreement under which Tehran would curb its nuclear program in exchange for sanctions relief.
The six powers want limits on Tehran's nuclear programs that could have a military use.
Tehran denies it is pursuing atomic weapons.
In Vienna, Iranian Foreign Minister Mohammad Javad Zarif said nuclear talks between the Islamic republic and world powers have been making progress and will continue to do so.
"We have made progress and we will make [more] progress," Zarif told reporters on July 1 after meeting with U.S. Secretary of State John Kerry.
"We will use every opportunity to make progress," he added.
Kerry later told reporters, "We have some very difficult issues, but we believe we are making progress and we are going to continue to work because of that."
Zarif added that Iran had invited the head of the UN nuclear agency to visit Tehran "to work with our officials on how to proceed."