Speaking to reporters on Thursday, Al-Baradai said Iran had agreed to facilitate the stricter, no-notice inspections by signing the Additional Protocol to the nuclear Non-Proliferation Treaty.
"I was assured that the Islamic Republic of Iran will clarify all the outstanding issues for us to able to verify all aspects of Iran's nuclear activities," Al-Baradai said after a meeting with Iran's Supreme National Security Council chief, Hasan Ruhani.
The nuclear watchdog chief said Ruhani has told him Iran will sign the additional protocol.
Al-Baradai's visit came just two weeks before a UN deadline for Iran to disprove US-orchestrated claims it has a secret atomic weapons programme.
"I was assured that the Islamic Republic of Iran will clarify all the outstanding issues for us to able to verify all aspects of Iran's nuclear activities"
UN Nuclear watchdog chief
Al-Baradai arrived in the Iranian capital overnight, warning that Iran had still not provided his agency the full disclosure it was seeking.
"I hope we will be able to clarify these issues and get a satisfactory answer," he said after meeting Ruhani.
Al-Baradai also said that despite agreeing to grant inspectors unlimited access, Iran had raised apprehensions about signing the additional protocol.
Iranian hardliners say unfettered access will be as good as sanctioning spying on the country.
"I made it very clear that all these apprehensions are unfounded. I mean the protocol is never meant in any way to compromise state sovereignty, security, dignity and technology development," Al-Baradai added.