The new hostages add to the three Japanese aid workers, two Palestinian residents of Israel and one Canadian worker taken hostage during an earlier wave of kidnappings this week.
Some of those detained have been released. Seven South Korean Christian missionaries were briefly held and later released Thursday. The New York Times reported the group proved their medical skills and paid their captors some $30,000 before they were freed.
Reuters reported that one of its journalists saw two captive foreigners, said by the insurgents to be Italians, being hauled into a mosque in a village in the Abu Ghraib district.
The insurgents, many of them masked, told the news service they had seized the men after stopping their vehicle on a road near the area. Other militants in the group said they had earlier taken two others who they said were Americans.
The Reuters journalist only saw two of the alleged Italian hostages, but the insurgents said they took four.
U.S. soldiers in a tank in the area near the village of al-Dhahab al-Abyad told Reuters they knew some Americans and other foreigners had been taken hostage, but had no details.
"That's why we are sealing off the road," said one soldier.
Neither Italian military authorities nor U.S. military authorities said they had information about any workers or personnel being abducted.
The kidnappings mark a possible new tactic by militants to try to pressure governments allied with the United States.
Prime Minister Junichiro Koizumi denounced the militants threatening to kill the Japanese hostages as "cowardly" and vowed Friday to keep Japan's troops in the country despite emotional pleas from the families of the captives.
Thousands in Japan massed near the prime minister's official residence and held a candlelight vigil for the captives.
The kidnappers have threatened to kill the hostages, two aid workers and a photojournalist, unless Japanese forces leave Iraq.
Television networks repeatedly aired dramatic video of militants holding the hostages at knifepoint and showing close-ups of their passports. The video footage was released Thursday by a previously unknown group calling itself the "Mujahedeen Squadrons."
The three were apparently seized as they entered Iraq on a highway from Jordan, according to The New York Times.
Koizumi called an emergency meeting of his Cabinet to discuss a response to the kidnappings. Vice President Dick Cheney visits this weekend, and the prime minister is expected to make a strong request for help.
A senior aide to radical Shiite Muslim cleric Muqtada al-Sadr denied on Friday that the religious leader's militia was involved in the kidnapping of three Japanese and threats to burn them alive.
The two Palestinians are residents of Israeli-controlled East Jerusalem. One of the two is employed by Research Triangle International, a North Carolina-based, independent non-profit organization that has a major reconstruction contract in Iraq.
The two were shown on Iranian television on Thursday along with Israeli identity cards, which Israel issues to East Jerusalem residents.
Palestinian Authority President Yasser Arafat intervened directly on Friday to seek their release, his office said.
"President Arafat has contacted our brothers in Iraq and other international bodies and friends today to help in releasing the two kidnapped Palestinians, Nabil George Razuq and Ahmed Yassin Tikati, both held in Iraq," a statement said.
A Syrian-born Canadian humanitarian worker, working for the New York-based relief group International Rescue Committee, was seized early on April 7.
A British civilian has also been reported missing in the southern Iraqi town of Nasiriyah. Coalition officials name him as a British contractor.