The United States has issued a visa to former Iranian President Mohammad Khatami, despite Washington's row with Tehran over its nuclear programme.
The US suspects Tehran of trying to build nuclear weapons
Mr Khatami will be one of the most senior Iranian figures to visit the US since diplomatic ties were cut in 1979, apart from officials on UN business.
Mr Khatami's visit is being described as private.
The US state department said there were no plans for him to meet government officials.
Mr Khatami is to give a speech at Washington's National Cathedral on 7 September on the role that Islam, Judaism and Christianity can play in shaping peace.
He will also attend a conference at the UN in New York on promoting dialogue.
State department spokesman Tom Casey said the visa allowed Mr Khatami, and several Iranians accompanying him, unrestricted travel in the US.
Mr Khatami was president of Iran from 1997 to 2005, when Mahmoud Ahmadinejad was elected.
Few Iranian leaders have visited the US since Washington cut diplomatic ties with Tehran when the American embassy in the Iranian capital was seized following the revolution in 1979.
Mr Khatami and President Ahmadinejad have both been to the UN in New York.
State department spokesman Tom Casey said: "This is an opportunity in part for former President Khatami to hear the concerns of the American people... He's going to get some tough questions from the American people who he does meet with."
The US has accused Iran of bankrolling terrorism around the world and suspects Tehran of trying to build nuclear weapons.
Tehran says its nuclear programme is for peaceful purposes only.
The UN has given Iran until 31 August to halt uranium enrichment - a possible route to nuclear weapons.
Last week, Tehran had offered "serious talks" in response to a package of incentives put forward by the five permanent UN Security Council members and Germany.
Iran could face sanctions if it does not suspend its nuclear programme.