Updated

The head of the U.N. nuclear watchdog agency said Tuesday that he cannot guarantee his probe of Iran's suspect nuclear activities will be complete by November, the deadline sought by the United States and its European allies.

Mohamed ElBaradei (search), the chief of the International Atomic Energy Agency (search), also repeated that his investigation has not definitely established whether Iran is trying to make nuclear weapons — as Washington asserts.

"We haven't seen any concrete proof that there is a weapons program," he told reporters. "Can we say everything is peaceful? Obviously we are not at that stage."

The meeting, which opened Monday, has become a main battleground for Iran and the United States, which wants to take Iran to the U.N. Security Council for alleged violations of the Nuclear Nonproliferation Treaty (search).

Diplomats attending the meeting said the United States was circulating a tougher version of a draft resolution originally written by France, Germany and Britain. The changes, designed to reduce Iran's wiggle room for dispelling suspicions about its nuclear activities, including the insertion of an Oct. 31 deadline.

The draft, summarized by the diplomat for The Associated Press, demands "complete, immediate and unrestricted access" to all sites and information requested by the agency in the two years since Iran's clandestine nuclear activities were revealed.

It also demands a complete list of nuclear materials and know-how imported by Iran, along with the black market suppliers and "immediate suspension" of all uranium reprocessing and activities related to uranium enrichment — both of which can be used to make nuclear bombs.

The draft does not directly threaten a referral to the Security Council. But by setting an Oct. 31 deadline, it indirectly makes clear the likelihood of that happening if Iran fails to fulfill all conditions, the diplomat said.

While ElBaradei said it was up to the board to decide whether to set a deadline, "we cannot just say there is a magic date."

"There is no artificial deadline where I can say, 'in November everything will be completed,'" he said.

Washington sought immediate referral as the meeting opened.

"The (U.S.) president wants Iran to answer to the Council, and that's where we're at now," a U.S. official said.

The European Union, long opposed to such a move, appeared to be inching toward Washington's position as it urged Tehran to give up work on uranium enrichment technology.

"There is a risk Iran is making a huge error," German Foreign Minister Joschka Fischer said Monday. "I hope they understand that. If not, we will end up in a very serious situation."

Fischer and 24 other EU ministers meeting in Brussels had hoped Iran would abandon its uranium enrichment program, which Iran says it needs to generate electricity but which other nations fear could be used to make nuclear arms.

Last week Iran confirmed an IAEA report that it planned to convert more than 40 tons of raw uranium into uranium hexafluoride, the feed stock for enrichment.

Enrichment does not fall under Iran's obligations under the Nuclear Nonproliferation Treaty, but Tehran has been under mounting international pressure to suspend the technology as a gesture to dispel suspicions it is interested in making weapons.

At the start of its meeting Monday, the agency's board of governors publicly focused on South Korea, which last week acknowledged past secret plutonium extraction and uranium enrichment experiments.

Plutonium and enriched uranium are two key ingredients of nuclear weapons.

ElBaradei described South Korea's failure to report those activities as a "matter of serious concern from the proliferation perspective."

Western diplomats revealed a link between tests conducted in 2000 and Seoul's secret uranium work in the 1980s, saying the connection cast doubt on Seoul's assertion that the experiments were the work of renegade scientists.

But South Korean delegate Ho Chang-Bom told reporters the amounts used in the experiments were small and performed by scientists "without the knowledge and authorization of the government."