A U.S.-led assault on a compound controlled by an extremist Islamic group turned up a list of names of suspected militants living in the United States and what may be the strongest evidence yet linking the group to Al Qaeda, coalition commanders said Monday.

The cache of documents at the Ansar al-Islam compound, including computer discs and foreign passports belonging to Arab fighters from around the Middle East, could bolster the Bush administration's claims that the two groups are connected, although there was no indication any of the evidence tied Ansar to Saddam Hussein as Washington has maintained.

There were indications, however, that the group has been getting help from inside neighboring Iran.

Kurdish and Turkish intelligence officials, some speaking on condition of anonymity, said many of Ansar's 700 members have slipped out of Iraq and into Iran -- putting them out of reach of coalition forces.

The officials also said a U.S. missile strike on Ansar's territory on the second day of the war missed most of its leadership -- which crossed into Iran days earlier.

U.S. officials said the government had reports some Ansar fighters could have made it into Iran and have been shuttling back and forth with fresh supplies.

According to a high-level Kurdish intelligence official, three Ansar leaders -- identified as Ayoub Afghani, Abdullah Shafeye and Abu Wahel -- were among those who had fled into Iran. The official said the three were seen being detained by Iranian authorities Sunday.

"We asked the Iranian authorities to hand over to us any of the Afghan Arabs or Islamic militants hiding themselves inside the villages of Iran," said Boorhan Saeed, a member of the pro-U.S. Patriotic Union of Kurdistan. "We asked them about it Sunday, and still don't have a response."

Last week, Secretary of Defense Donald Rumsfeld warned the Iranians to stop meddling in the war. Tehran denied any involvement.

Using airstrikes and ground forces, Kurdish soldiers and U.S. troops have cooperated in the past week to dislodge and crush Ansar militants in 18 villages surrounding the Iraqi city of Halabja -- about 160 miles northeast of Baghdad.

"We actually believe we destroyed a significant portion of the Ansar al-Islam force there," Maj. Gen. Stanley McChrystal, vice director of operations on the Pentagon's Joint Staff, said Monday. He said forces were investigating the finds.

Among a trove of evidence found inside Ansar compounds were passports and identity papers of Ansar activists indicating that up to 150 of them were foreigners, including Yemenis, Turks, Palestinians, Pakistanis, Algerians and Iranians.

Coalition forces also found a phone book containing numbers of alleged Islamic activists based in the United States and Europe as well as the number of a Kuwaiti cleric and a letter from Yemen's minister of religion. The names and numbers were not released.

"What we've discovered in Biyare is a very sophisticated operation," said Barham Salih, prime minister of the Kurdish regional government.

Seized computer disks contained evidence showing meetings between Ansar and Al Qaeda activists, according to Mahdi Saeed Ali, a military commander.

It was unclear how strong Ansar remains.

Officials from the Patriotic Union of Kurdistan, one of two parties that share control of an autonomous Kurdish enclave in northern Iraq, say they killed 250 Ansar members during two days of intense fighting and aerial bombardments.

"There was ferocious fighting," Saeed said. He said he chased 25 Ansar militants across the Iranian border and captured nine Ansar sympathizers belonging to a group called the Islamic Movement of Kurdistan.

The remaining Ansar fighters are thought to be in the mountains along the Iraq-Iran border, U.S. and Kurdish military officials have said.

Kurdish soldiers on Monday continued sporadic fighting in several villages around Halabja and along the Iran-Iraq border near the village of Sargat, site of a destroyed building once allegedly used by Ansar militants to produce poison.

Gen. Richard Myers, chairman of the Joint Chiefs of Staff, said Sunday the Sargat compound was probably the site where militants made a biological toxin, traces of which were later found by police in London.

"We think that's probably where the ricin that was found in London came [from]" he said in a televised interview. "At least the operatives and maybe some of the formulas came from this site."

British police raided a London apartment in January and found traces of ricin, a powerful poison made from castor plant beans. U.S. officials believe the poison and those arrested were linked to Ansar.

The group's leader, Mullah Krekar, is being held in Norway on charges of kidnapping and aiding terrorists.

Krekar has denied any links to Saddam or Al Qaeda, but said he considers Usama bin Laden a "good Muslim."

In a recent interview with Dutch television, Krekar said his fighters would use suicide attacks if U.S. troops went after the group.

One such attack came three days into the war when an apparent car bomb killed at least five people, including an Australian cameraman, at a checkpoint near an Ansar training camp.