"A meeting between Iran and the agency has been scheduled for 8 June in Vienna," Amano told the International Atomic Energy Agency's 35-member board of governors at the start of a week-long meeting.

"I invite Iran to sign and implement the Structured Approach document as soon as possible and to provide early access to the Parchin site," Amano said, referring to a military base near Tehran.

The IAEA is seeking an accord with Tehran to guarantee swift and unconditional access to sites, people and documents related to the Islamic republic's nuclear programme.

After a visit to Tehran on May 21, where he met Iran's chief nuclear negotiator Saeed Jalili, Amano said an accord could be signed "quite soon," but there is still no sign of any agreement.

Part of the agreement would involve the Parchin base, where the IAEA believes suspicious explosives testing was carried out.

The agency has been seeking access to the site for months, but has so far been denied by Iran, which says Parchin is of no relevance to its nuclear programme and it is not obliged to allow inspections.

In its latest report last month, the IAEA said new satellite imagery of Parchin indicated "extensive activities" at the base, including the razing of two buildings and what experts have described as a clean-up at the base.

This "could hamper the agency's ability to undertake effective verification" of the site, the IAEA report warned.

US Treasury Undersecretary David Cohen said in an interview with the newspaper the sanctions would be imposed if talks in Russia slated for mid-June failed to halt Iran's nuclear programme.

Iran and the so-called P5+1 powers, comprising the United States, Russia, France, Britain, China and Germany, have held two rounds of talks already, and are scheduled for third meeting in Moscow on June 18-19 as a July 1 deadline looms for the enforcement of an EU embargo on Iranian oil.

"If we don't get a breakthrough in Moscow there is no question we will continue to ratchet up the pressure," said Cohen, who coordinates US sanctions policy against Iran.

"The important point for the Israeli public to understand and for the Iranian leadership to understand is that if we are not able to make progress on the diplomatic track there is additional pressure that can be brought to bear on the pressure track."

Cohen, who arrived in Israel on Sunday for talks on sanctions against Syria and terrorist financing, said Washington was consulting closely with Israel on the issue, Haaretz reported.

"We have today and over the past years had very close cooperation with the Israeli government across a range of our sanctions programmes. They are a very good partner. They are creative. They are supportive and we will continue to consult with the Israelis," he said.

The international community has been pursuing a negotiated solution to Iran's nuclear programme, which Tehran insists is for peaceful civilian energy and medical purposes but the international community believes hides a weapons drive.

Israel, the Middle East's sole if undeclared nuclear power, has warned that an Iranian nuclear capability would pose an existential threat to the Jewish state.

It has consistently warned that all options remain on the table to prevent Iran from going nuclear, including a military strike.