Investigators on Thursday questioned an Iraqi suspected of recruiting Islamic fighters to carry out attacks against U.S. forces in Iraq, following similar arrests last week in Hamburg (search) and Milan.

The earlier arrests were part of an Italian probe into a cell thought to be recruiting fighters or homicide bombers for the northern Iraq-based militant group Ansar al-Islam (search). German officials Thursday suggested the latest arrest, in Munich, was linked.

"Almost all of the people arrested in recent times had contact among each other," Ulrich Kersten, head of Germany's Federal Criminal Office, told a news conference, without elaborating.

Munich police arrested the Iraqi on Tuesday at the southern German city's main train station fearing he was about to flee the country, prosecutor August Stern said.

The suspect was arrested on a warrant on charges of illegally smuggling Iraqis into Germany, Stern said. But media reports said investigators also believe he was recruiting for Ansar al-Islam, a group U.S. officials believe has links to Al Qaeda (search).

Referring to the Munich arrest, Bavaria's top security official, Guenter Beckstein, said Thursday that state authorities "have had an eye for a long time" on Ansar al-Islam. The group has about 100 supporters in Germany, according to Bavarian authorities.

The Sueddeutsche Zeitung reported Thursday that the 29-year-old Munich suspect leads Ansar's local cell and recently organized trips to Iraq for up to a dozen people for possible homicide bombing missions against U.S. troops. A second suspect was at large, the paper said.

On Nov. 28, police in Hamburg acting on an Italian warrant arrested Abderrazak Mahdjoub, an Algerian believed to have links to Al Qaeda. That followed the arrests in Milan of a Tunisian and a Moroccan.

The Italian government said the arrests grew out of an investigation of a ring suspected of seeking recruits for a training camp run by Ansar al-Islam. Mahdjoub is suspected of being the ringleader.

Italian investigators have said Mahdjoub had contacts with two key Ansar al-Islam suspects arrested during raids in Italy in March and April -- Mohamed Daki, a Moroccan, and Ciise Maxamed Cabdullaah, a Somali.

German officials said they scrambled to arrest the Iraqi, whose name was not released by authorities, after the Bild newspaper reported Tuesday that a suspect jailed in Italy had fingered a Munich cell as financing and organizing Ansar al-Islam's recruitment.

"We had to make our grab sooner than we wanted," Bavaria's criminal police chief, Heinz Haumer, told Sueddeutsche Zeitung.

Authorities seized evidence during searches of apartments after the arrest, Stern said. Federal prosecutors, who are responsible for terrorist cases, were examining whether to formally enter the investigation, spokeswoman Frauke Scheuten said.

In Hamburg -- the city where three of the Sept. 11 homicide hijackers lived and studied -- a security official in charge of tracking extremists said authorities have about a dozen people under observation there as potentially leading Islamic radicals.

Heino Vahldieck, head of the city's Office for the Protection of the Constitution, indicated these suspects included Mahdjoub, who was arrested as a terror suspect in July but let go for lack of evidence until his renewed arrest on the Italian warrant.