Olli Heinonen, deputy director general of the International Atomic Energy Agency (IAEA), told journalists that the inspectors would visit the half-built plutonium-producing reactor either on Monday or Tuesday.

Heinonen was speaking after talks in Vienna with Iran's deputy national security chief Javad Vaeidi and IAEA ambassador Ali Asghar Soltanieh on finalising a plan to clarify "open issues associated with the scope and content of Iran's enrichment programme."

"We had good discussions. We made constructive progress," Vaeidi told reporters, adding that the next meeting would take place on August 20 in Tehran.

Iran said on July 13 that it would let IAEA inspectors visit the Arak reactor, which is currently under construction and should be completed in 2009.

The UN Security Council has imposed two rounds of sanctions to get Tehran to cease enriching uranium, to stop building Arak and to cooperate fully with IAEA inspectors -- and there are calls for a third round.

Several diplomats have warned that Iran, by allowing inspections of Arak, might just be stalling in order to avoid more sanctions.

Iran has rejected any halt in its enrichment work, insisting that its nuclear activities are a peaceful effort to generate electricity.

The United States has led international charges that it is hiding a covert nuclear weapons programme.

Tuesday's talks had been aimed in part at agreeing a working framework of "precise rules" concerning any inspections of Tehran's nuclear facilities.

IAEA chief Mohamed ElBaradei hailed last week Tehran's decision to allow the inspections and its willingness to discuss its nuclear programme as "a positive move".

"I hope that we will continue on that road," he said during a visit to Malaysia.

"We require a consistent effort by Iran to work with us and we also require the international community to understand that this is a complex process that will take some time."

But "the earlier we are able to say that the Iranian programme is exclusively for peaceful purpose, the better for Iran, the better for the international community," he said.

Iran had blocked access to Arak since April in an escalating crisis over its nuclear activities that some fear could lead to US or Israeli military strikes.

Iranian Foreign Minister Manouchehr Mottaki was quoted by French daily Le Monde on Tuesday as saying that the United States "is not in a position" to launch military action against Iran over the issue.

"The Americans are not in a position to inflict a new war on the American taxpayer," he said, adding that this "does not, it is true, stop some people from banging the war drums."

Experts believe that when it is up and running, Arak will be able to produce 12.5 kg of plutonium each year, enough for two or three nuclear bombs.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.