The meeting in Tehran will be the first since Iran and six major powers agreed on April 2 the main outlines of potentially historic deal curtailing Iran's nuclear activities in return for sanctions relief.

Western officials say it is crucial for Iran to answer the International Atomic Energy Agency's long-standing questions about the "possible military dimensions" of its activities before any sanctions can be eased.

Iran rejects the allegations as false information provided to a gullible and partial IAEA by the Islamic republic's enemies, complaining that it has not even been given an opportunity to see much of the supposed evidence itself.

Under the April 2 agreement, Iran agreed to scale back dramatically its nuclear programme and submit to ultra-tight IAEA inspections in order to make any dash to make a nuclear bomb extremely difficult and easily detectable.

The accord has to be finalised by June 30. However, experts warn that hammering out the details will be tough, given resistance from some in Washington and Tehran, as well as bitter opposition from Israel and across the wider Middle East.

The Vienna-based IAEA said in Monday's brief statement that its delegation at Wednesday's "technical meeting" will be headed by chief inspector Tero Varjoranta.

Israel slams Russia decision to lift Iran missile ban
Jerusalem (AFP) April 13, 2015 - Israel on Monday denounced Russia's decision to lift a ban on supplying Iran with sophisticated S-300 air defence missile systems as proof of Tehran's newfound "legitimacy" following nuclear talks.

"This is a direct result of the legitimacy that Iran is receiving from the nuclear deal that is being prepared, and proof that the Iranian economic growth which follows the lifting of sanctions will be exploited for arming itself and not for the welfare of the Iranian people," Israeli Intelligence Minister Yuval Steinitz said in a statement.

Moscow's decision to lift the ban comes after a major breakthrough in talks between world powers and Iran over its disputed nuclear programme, which saw the parties agreeing on a framework deal on April 2.

The emerging deal, which is to be finalised by June 30, would see Iran would curtail its nuclear activities in exchange for relief from punishing economic sanctions, sparking a welter of harsh criticism from Israel.

"As Iran disavows clause after clause of the framework agreement... the international community has already begun implementing easing measures," he railed.

"Instead of demanding that Iran stop its terrorist activity in the Middle East and the world, it is being allowed to arm itself with advanced weaponry that will only increase its aggression."

Russia is a key supplier of arms to the Arab world, including governments which do not recognise the Jewish state, and its weapons exports have long been of concern to Israeli leaders who have sought to persuade Moscow to scale down its cooperation Iran and Syria.

The S-300 batteries are advanced ground-to-air weapons that can take out aircraft or guided missiles.

The decree, signed by President Vladimir Putin on Monday, ends a ban on the deliveries of S-300 missiles to Iran which was put in place in 2010 after the United Nations slapped sanctions on the Islamic Republic over its nuclear programme, including barring the sale of hi-tech weaponry.