Evidence has been found in the Kurdish-controlled regions of northern Iraq that the Islamic militant group Ansar al-Islam was working on three types of chlorine gas and ricin and has ties to Al Qaeda, U.S. officials told Fox News.

Officials said that between 75 and 150 Al Qaeda members have been captured or killed in northern Iraq in recent days.

U.S. sources told Fox News that documents and equipment were found in the rubble of an Ansar facility that had been built into a cliff near Sargat. The material was described as "a cookbook and kitchen" for chemical weapons.

Other items included latex gloves, penicillin, a freezer and lab equipment. Sources said additional tests are planned.

Two suspected Al Qaeda members escaped into Iran but surrendered to the Iranian Revolutionary Guards. Iran has said it will hand over captured Ansar members. U.S. officials are waiting for them.

There were indications earlier that Ansar al-Islam was getting help from inside neighboring Iran.

Kurdish and Turkish intelligence officials said many of Ansar's 700 members have slipped out of Iraq and into Iran.

Earlier this week, a coalition assault on a compound controlled by Ansar al-Islam in Biyare, northern Iraq, turned up lists of names of suspected militants living in the United States.

Coalition troops found computer discs and other materials belonging to Arab fighters from around the Middle East. The findings could be the strongest evidence yet to support the Bush administration's arguments that the Iraqi-based group is connected to Al Qaeda.

A high-level Kurdish intelligence official said 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. Fox News confirmed that Afghani was one of the fugitives.

"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."

Among the 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.

"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.

Fox News' Carl Cameron and The Associated Press contributed to this report.