Some within the U.S. intelligence community think Osama bin Laden is in eastern Iran, instead of the rugged tribal areas of Pakistan's northwestern frontier, where most American officials think he is still on the run.
U.S. officials said in interviews that the Iran theory, which is held by a minority, is based on bits of intelligence information and the fact that months of CIA intelligence operations, along with search-and-destroy sweeps by thousands of Pakistani troops, have failed to find the al Qaeda leader or his No. 2, Ayman al-Zawahri.
Asked whether the U.S. intelligence community thinks bin Laden may be in Iran, a senior administration official told The Washington Times, "Some people think he is."
That source said there is great frustration, especially within the inner circle around Defense Secretary Donald H. Rumsfeld, that bin Laden has not been caught or even unequivocally spotted in Pakistan's border region. The frustration is fueling speculation that bin Laden may not be there after all.
Rep. Curt Weldon, Pennsylvania Republican and House Armed Services Committee member, writes in his new book, "Countdown to Terror," that a reliable Iranian source he identifies only as "Ali" told him that bin Laden has been in Iran for some time.
"The course of world events have established incontrovertibly that Ali is a high credible source of reliable intelligence on Iranian and other terrorist activities," Mr. Weldon writes.
But the Bush administration's official position is that bin Laden is most likely in the border region straddling Pakistan and Afghanistan and that he is hidden by tribal allies.
"The consensus is that bin Laden remains in the border region," said a U.S. intelligence official.
Asked about reports that bin Laden is in Iran, which borders both Pakistan and Afghanistan, the official said, "That would be a big risk for the Iranians. ... There are all kinds of rumors that these guys go in and out of Iran, but that always struck me as odd."
Bin Laden lived near Kandahar, Afghanistan, the Taliban cultural headquarters, until the 2001 U.S. invasion. He moved north to the Tora Bora mountain range, then slipped across the border into Pakistan.
Gone are the heady predictions of early 2004, when the U.S. command in Afghanistan predicted bin Laden would be killed or captured by year's end. No commander is making such predictions now, and privately, some officers say the trail has gone cold.
Bush administration officials have accused Iran, a U.S.-designated sponsor of terrorism, of harboring al Qaeda lieutenants who escaped from Afghanistan in 2001.
The administration has stopped short of providing the names of the al Qaeda fugitives or suggesting that bin Laden is among them.
The U.S. also has intelligence that Abu Musab Zarqawi, who heads al Qaeda in Iraq, has slipped in and out of Iran since 2003 to evade capture. Officials say that is why Mr. Rumsfeld and the new Iraqi government have publicly warned Iraq's neighbors not to take in Zarqawi, whom Islamic Web sites say was wounded and needed medical care.
Washington thinks one of bin Laden's sons as well as a top operations chief are in Iran.
Iran denies harboring al Qaeda, but has said it has arrested and detained some members.