Six of the men named in an FBI terrorism alert this week are in custody in Yemen and elsewhere and have been removed from the list of those being sought, officials said Thursday.

The officials said the FBI had placed on Monday's nationwide alert all 17 names of men they feared might be plotting an attack on U.S. interests as early as Tuesday even though they suspected some were already in custody.

The FBI has since confirmed that six of the men are in custody — most in Yemen and at least one outside the Middle East, the officials said.

"Given the urgency of information indicating the possible attack within 24 hours, an alert was issued. Today, we have received information that at least six possible associates of al-Rabeei may be in custody in the Middle East or elsewhere," FBI spokesman John Collingwood said.

The FBI removed the men's pictures and names from the alert. They are:

— Issam Ahmad Dibwan al-Makhlafi

— Ahmad al-Akhader Nasser Albidani

— Bashir Ali Nasser al-Sharari

— Abdulaziz Muhammad Saleh bin Otash

— Shuhour Abdullah Mukbil al-Sabri

— Riyadh Shikawi

The FBI continues a worldwide manhunt for the 11 others, including suspected ringleader Fawaz Yahya al-Rabeei of Yemen.

Meanwhile, U.S. officials reacted skeptically Thursday to a report from Tehran that Iranian authorities have arrested a multinational group of some 150 people and are questioning them about possible links to the Taliban or Al Qaeda.

The report, carried by the Islamic Republic News Agency, said the information was provided by an unidentified source. The detainees are said to include European and African nationals who were carrying passports from countries such as France, Britain, Belgium, Spain and The Netherlands.

During questioning thus far, the report said, none of the detainees has been connected to either the Taliban or Al Qaeda.

The report said those arrested had entered Iran from Pakistan. Many had spent time in Afghanistan at some stage before arriving in Iran, it said.

The State Department had no independent information on the subject, an official said, partly because there is no U.S. diplomatic presence in Iran.

Another official suggested that the report could be a propaganda ploy by Iran to counter President Bush's contention that Iran is part of an "axis of evil."

CIA Director George J. Tenet said last week that Tehran has failed "to move decisively against Al Qaeda members who have relocated to Iran from Afghanistan."

The administration also has complained that Iran, a neighbor of Afghanistan, has armed and financed fighters to destabilize the government of interim Prime Minister Hamid Karzai.

At the same time, the administration also has taken note of positive actions that Iran has taken toward Afghanistan.

As examples, U.S. officials have cited the support Iran provided for the diplomatic process that led to the installation of the interim government.

They also have praised an Iranian pledge to provide $550 million in reconstruction assistance to Afghanistan over five years.

The officials said Iran's seemingly contradictory behavior toward Afghanistan could reflect Iran's two-tier system of government, with the more moderate elected authorities in charge of some ministries and unelected hard-line clerics controlling others.