The head of the International Atomic Energy Agency (search) urged North Korea (search) on Tuesday to back away from its nuclear threat and asked Iran to improve cooperation with his organization's investigation of its nuclear activities.

Adding to proliferation concerns, a confidential European Union document made available to The Associated Press showed Saudi Arabia defying the United States, the EU and Australia by insisting it will not permit U.N. nuclear experts to verify claims that it has nothing worth inspecting.

The EU memo was given the AP on the sidelines of an IAEA board meeting that plans to discuss the Saudi issue later this week along with focusing on North Korea and Iran.

The Saudis insist they have no plans to develop nuclear weapons. But they have been under pressure to allow nuclear inspectors to come into the country before an IAEA deal comes into force that would effectively curtail the agency's monitoring powers in the country.

Called the small quantities protocol, the deal has been implemented in more than 70 countries, most of them small and in politically stable areas of the world. It basically allows countries to escape verification of their claims that their nuclear activities are below the minimum threshold the agency considers worth inspecting.

But the Saudi push to formalize minimal monitoring for the country comes amid increased nuclear-generated tensions in the region, fed by suspicions that rival Iran might want to develop the bomb.

While the Saudi government insists it has no interest in going nuclear, in the past two decades it has been linked to prewar Iraq's nuclear program, to Pakistan, and to the Pakistani nuclear black marketeer A.Q. Khan (search). It also has expressed interest in Pakistani missiles capable of carrying nuclear warheads, and credible reports say Saudi officials have discussed taking the nuclear option as a deterrent in the volatile Middle East.

In recent weeks, the United States, the European Union and Australia had urged the Saudis in separate diplomatic notes to either back away from the small quantities protocol or to at least agree to inspections despite implementing it.

But the EU briefing memo — made available to the AP by a diplomat accredited to the agency who insisted an anonymity because he was not authorized to give it to the media — showed Saudi unwillingness to bow to Western pressure.

It quoted Saudi deputy foreign affairs minister, Prince Turki bin Mohammed bin Saud al-Kabira as saying his country would be "willing to provide additional information" to the agency "only if all other parties" to the small quantities protocol did the same.

While the IAEA is also concerned about North Korea, it has no purview over the country since its inspectors were ordered to leave in late 2002. Since then, the country has increased threats to develop — and possibly use — nuclear weapons against a perceived threat from the United States.

Mohamed ElBaradei (search) told delegates said his agency stands ready to work with North Korea "to ensure that all nuclear activities ... are exclusively for peaceful purposes."

Iran, in contrast, has been the focus of an intense agency investigation since 2003, following revelations of nearly two decades of secret nuclear activities. The work included uranium enrichment, which can be used to make the core of nuclear warheads.

Iran insists it wants to enrich only to generate nuclear power, but froze that program and linked activities late last year as it focused on talks with France, Britain and Germany meant to reduce concerns about Tehran's nuclear ambitions.

While providing some information to help agency investigations, Iran's cooperation has not been sufficient, said ElBaradei, in particular on details of its enrichment program sought by the agency to verify whether Tehran only wants to generate power with the technology.

ElBaradei also urged Iran to allow agency visits to Lavizan and Parchin.

Parchin is a military site where the United States says Iran may be testing high-explosive components for nuclear weapons. A previous visit by agency inspectors was strongly restricted by the Iranians. The Lavizan-Shian site near Tehran is an area where the agency believes Iran has stored dual-use equipment that can be used both for peaceful and nuclear weapons-related purposes.