The International Atomic Energy Agency has acknowledged it wrongly accused Iran of withholding some information about its nuclear program. But the agency still says Iran has not been cooperative enough in the investigation of the program and the agency's board is still expected to pass a strongly-worded resolution calling on Iran to do more.

The head of the IAEA, Mohamed ElBaradei, acknowledged the mistake Thursday, but said the information about the purchase of special magnets was only provided verbally, not in writing. He said the misunderstanding proves that Tehran should provide prompt and full information to the agency.

But Iran's chief negotiator with the IAEA, Seyed Hossein Mousavian, described the IAEA's mistake as big, and said it proves the information Iran has been providing is, in his words, full and precise. He said the disclosure means that Mr. ElBaradei's allegation that Iran has not been cooperating fully is completely wrong.

Mr. ElBaradei disagrees. He says this is only one small discrepancy in the IAEA's report on Iran, the rest of which is valid. That assessment is the basis for a draft resolution the agency's board is expected to pass this week, expressing concern at Iran's lack of cooperation and calling for full disclosure of its nuclear activities.

A western diplomat said Thursday's disclosure could result in some changes to the resolution, but said it will still be the toughest since the IAEA first looked at the Iranian nuclear program a year ago.

If Iran does not comply, the issue could be referred to the U.N. Security Council. Iran says its nuclear program is for peaceful purposes only. But the IAEA is concerned it could be aimed at developing nuclear weapons, as the United States and other countries believe.

On Wednesday, Iran threatened that if the IAEA passes a strong resolution, it would consider ending its cooperation with the agency, and might resume enriching uranium, which could be a prelude to building a nuclear bomb.