Secretary of State Colin Powell (search) on Monday insisted that Iran hand over senior terror suspects even as U.S. intelligence evaluates a list of 225 suspected operatives provided to the United Nations by the Tehran government.

How Iran (search) responds -- and how serious is its offer to cooperate with the International Atomic Energy Agency (search) -- could determine whether the Bush administration tries to reverse more than two decades of diplomatic disconnect.

On Sunday, Iranian Foreign Minister spokesman Hamid Reza Asefi said Iran last month gave the U.N. Security Council the names of 225 suspected Al Qaeda (search) operatives it had detained after they had crossed the country's border.

But Powell told reporters Monday that the administration was seeking "clarification" of the information Iraq had provided to the United Nations.

Meanwhile, he insisted that any Al Qaeda operatives held by Iran should be turned over to their country of origin or to the United States for interrogation and trial.

Iran in the past has turned over some suspects, but Richard Boucher, the State Department spokesman, said: "We are not aware of any particular progress with regards to the Al Qaeda who are currently in detention."

And, Boucher said, the Iranians themselves have said they were holding senior officials of the terror network headed by Usama bin Laden.

American counter-terrorism officials said last week that a handful of senior Al Qaeda operatives who fled to Iran after the war in Afghanistan two years ago may have developed a working relationship with a secretive military unit linked to Iran's religious hard-liners.

The U.S. government isn't certain of the extent of the contacts with the Iranian unit, called the Qods Force, said the officials, who spoke on condition of anonymity.

U.S. officials have said intelligence suggests that Al Qaeda figures in Iran include Saif al-Adl, a top Al Qaeda agent possibly connected to bombings in Riyadh, Saudi Arabia, last May; Abu Mohammed al-Masri, wanted in connection with the bombings of two U.S. embassies in East Africa in 1998; Abu Musab Zarqawi, whom some U.S. officials describe as the key link between Al Qaeda and toppled Iraqi leader Saddam Hussein; and Usama bin Laden's eldest son, Saad.

The Al Qaeda operatives are believed to have fled to Iran from neighboring Afghanistan during the Taliban's fall in late 2001 or early 2002.

Iranian spokesman Asefi, when asked Sunday how many Al Qaeda operatives were in Iranian custody, said only they had "a number of them." He said Iran would not reveal the number and names of Al Qaeda suspects in custody for security reasons.

Intelligence Minister Ali Yunesi confirmed for the first time in July that Iran was holding "a large number of small and big-time elements of Al Qaeda."

On the nuclear front, Iran last week promised European governments it would expand IAEA inspections and suspend enrichment of uranium in response to suspicions it is developing a nuclear weapons program.

"We're looking for action," Boucher said, sounding a skeptical note. Until that happens, the spokesman said he could not speculate on any improvement in relations.