The tape showed the two engineers, identified by relatives as Thomas Nitzschke and Rene Braeunlich, seated on the floor with at least four armed men standing behind them.
The timer shown in the corner of the tape, aired by Al-Jazeera television, indicated it was filmed at 10:08 on Jan. 24, less than two hours after they were abducted in the northern industrial city of Beiji, 155 miles north of Baghdad.
"The (German) government condemns this cruel kidnapping in the strongest possible terms," Chancellor Angela Merkel said after a video of the two men was aired. "We appeal urgently to the perpetrators to release our two compatriots without delay."
The German hostages were seen speaking but Al-Jazeera did not broadcast any audio and the station did not report any demands beyond the hostages calling for German government intervention to secure their release.
A handwritten black banner was shown on the tape reading: "Supporters of Tawhid and Sunnah Brigades," a previously unknown group. Tawhid is the Arabic word for monotheism and Sunnah refers to the teachings of the prophet Muhammad.
In other developments:
A U.S. spokesman says a gun battle broke out at a checkpoint in Kirkuk, 180 miles north of Baghdad, and three men wearing Iraqi police uniforms inside a car were shot dead. American troops captured a fourth man from the car, but found no police identity documents on the men. The military says two U.S. soldiers were killed Saturday in separate roadside bomb blasts.
German Foreign Minister Frank-Walter Steinmeier said the German government would do everything it can to secure the engineers' release.
An Al-Jazeera editor, who declined to be identified because he was unauthorized to speak to the media, said the tape was only about 35 seconds long. He declined to say how the tape was obtained.
Nitzschke and Braeunlich arrived in Iraq on Jan. 22 and only planned to remain "for a short time," the German Foreign Ministry said.
Their employers, Leipzig-based Cryotec Anlagenbau AG, have a commercial relationship with an Iraqi government-owned detergent company in the industrial town of Beiji, where Brazilian engineer Joao Jose Vasconcelos Jr., was also kidnapped on Jan. 19, 2005. His whereabouts remain unknown.
At least five foreigners have been kidnapped in Iraq this month, including two Kenyan communications engineers missing after an ambush in Baghdad on Jan. 18 and American journalist Jill Carroll, who was seized Jan. 7 in the capital. Her translator was killed.
Carroll's kidnappers have threatened to kill the 28-year-old freelancer unless all Iraqi women are freed from custody.
The U.S. militaryThursday, and a top Iraqi police official expressed hope the move might help win Carroll's freedom.