The head of the United Nations nuclear agency says he expects Iran to sign an agreement “quite soon” to allow inspections of facilities suspected of being used in a covert nuclear weapons program.

International Atomic Energy Agency chief Yukio Amano made the comment Tuesday after returning to Vienna from a brief visit to Iran where he met chief Iranian nuclear negotiator Saeed Jalili. Amano said he and Jalili made a “decision to reach an agreement” on U.N. access to Iranian sites including the Parchin military complex.

Western powers suspect Iran has engaged in atomic weapons research at the site. Tehran says Parchin is a conventional weapons facility and insists the Iranian nuclear program is peaceful.

Israel sees a nuclear-armed Iran as a threat to its existence and refuses to rule out military action against the Iranian nuclear program. Israeli Cabinet minister Matan Vilnai dismissed the prospect of an imminent IAEA agreement, saying Tuesday that Israel has to be “suspicious of Iran all the time” due what he called Tehran's record of deceit.

Amano said some differences remain between the IAEA and Iran on the nuclear issue and he is not sure when they will be resolved. But, he also said Jalili assured him those differences will not be an obstacle to a deal.

Representatives of six world powers are preparing to meet with Jalili in Baghdad on Wednesday to try to negotiate a separate agreement for Iran to stop producing highly-enriched uranium that could be converted quickly to nuclear bomb material.

It is not clear how Amano's apparent progress with Iran on IAEA inspections will affect the Baghdad negotiations on enrichment.

Acting U.S. envoy to the IAEA Robert Wood said Washington remains “concerned” by what he called Iran's “urgent obligation” to cooperate fully with the U.N. nuclear agency in resolving suspicions about the nature of the Iranian nuclear program.

The United States also has refused to rule out a strike on Iran to prevent it from obtaining nuclear weapons.

On Monday, Israeli Prime Minister Benjamin Netanyahu urged the six world powers negotiating with Iran to avoid concessions and to show “determination and not weakness” in the Baghdad talks.

Israel is widely believed to be the only nuclear-armed nation in the Middle East.