Eleven kidnapped Iraqi National Guardsmen were shown being killed in a video posted Thursday on the Internet, extending a succession of recent slayings of Iraqi and foreign security forces by insurgents.

Two U.S. soldiers were also killed Thursday, and a Polish woman was added to the ranks of foreigners taken hostage in Iraq.

The Ansar al-Sunna Army, an Islamic group that also asserted responsibility for the almost identical execution of 12 Nepalese workers in August, posted warnings to other Iraqi security forces with the footage of the guardsmen's deaths -- the first by beheading, the others by gunshot. Each victim recited his name and unit before being killed.

"Abandon your weapons and go home and beware of supporting the apostate Crusaders or their followers, the Iraqi government, or else you will only find death," an unidentified voice said in Arabic on the soundtrack. A written statement on the site added: "We will not forget about the blood of our elderly, women and children that is shed daily in Fallujah, Samarra, Ramadi and elsewhere on your hands and the hands of those you work with."

The insurgent group announced last week that it had kidnapped the 11 guardsmen. Iraq's Defense Ministry said Thursday, however, that it had not received any reports that 11 guardsmen were missing, news services reported.

The National Guard, one of a handful of Iraqi security agencies established after the U.S.-led invasion last year, has borne the brunt of insurgent attacks aimed at forces defending Iraq's interim government. Most recently, 49 unarmed National Guard recruits were massacred by unknown gunmen Saturday near a training base northeast of Baghdad.

The U.S. soldiers slain Thursday were attacked in the kind of ambushes that have become common in Iraq. One soldier was killed when a huge car bomb exploded beside a convoy under a freeway overpass in southern Baghdad. The second died in a rocket-propelled grenade attack on a convoy between Baghdad and Balad, a huge logistics base north of the capital. The military withheld the names of the soldiers pending notification of next of kin.

In the latest kidnapping, a middle-age woman identified as a Polish national was displayed on a video aired by al-Jazeera, the Qatar-based satellite news channel. The woman was shown sitting calmly before two masked men, one of whom pointed a pistol at her head. Al-Jazeera reported that the woman could be heard urging Poland to pull its troops out of Iraq. Poland has about 2,400 troops in the country's south.

Polish Foreign Minister Wlodzimierz Cimoszewicz said the woman was a Polish citizen married to an Iraqi and worked at the Polish Embassy in Baghdad in the 1990s, according to the Associated Press. President Aleksander Kwasniewski, often praised by President Bush as a stalwart ally on Iraq, declared that Poland would not surrender "to the dictate of terrorists."

The kidnapping was at least the third in 10 days involving a citizen of a country that has provided troops to the U.S.-led military coalition.

Margaret Hassan, the CARE International country director who also has an Iraqi husband, was seized Oct. 19 and has been shown in Internet videos pleading for British Prime Minister Tony Blair to quit the coalition. Hassan, a native of Ireland, also has British and Iraqi citizenship.

On Thursday, the charity, which earlier had suspended operations here, announced it was closing entirely in Iraq and repeated its call for Hassan's release.

There was no word on the fate of a third hostage, Shosei Koda, the Japanese backpacker who had warned in a video that he would be beheaded by Thursday unless the Tokyo government pulled out its troops. Prime Minister Junichiro Koizumi has refused the demand.

[The Japanese government convened an emergency session Friday following a media report that a body believed to be Asian was found in Iraq, according to the Associated Press. "We haven't confirmed anything yet," Koizumi said.]

In yet another video display, a band of masked men claimed that insurgents had acquired "a large quantity of explosives" from Qaqaa, the arms facility from which a U.N. agency says tons of high explosives had disappeared.

No support was offered for the claim, made by a group calling itself the Islam Army Brigades Karrar Brigade. One analyst said Iraq had more than 900 munitions sites before the invasion, and insurgents have long boasted that arms and explosives were readily available.

As if to prove the point, residents of Fallujah said a shipment of explosives, assault rifles, rockets and missiles recently was smuggled into the city in a tank truck. The city, under the control of local insurgents and foreign fighters since April, is preparing for an expected U.S. military offensive intended to restore Baghdad's authority before national elections promised for January.

Informal talks aimed at averting military action in Fallujah continued Thursday, but the office of interim Prime Minister Ayad Allawi warned in a statement, "This chance could be the last."

U.S. warplanes bombed a house before dawn in Fallujah's battered Jolan neighborhood, killing three fighters inside, residents said. And in a helicopter raid, U.S. forces arrested a leader of Mohammad's First Army, Nouri Halboosi, in Halabsa, west of Fallujah.

A man cries for his slain son next to the charred civilian vehicle the man was driving when insurgents set off a car bomb targeting a U.S. convoy in Baghdad. A former employee of the Polish Embassy in Baghdad is the latest in a series of foreigners taken hostage.