Sat Dec 30, 10:31 PM ET
VIENNA, Austria - Austria's Foreign Ministry said Saturday that experts examined an audio tape of four American security contractors and an Austrian kidnapped in
Iraq six weeks ago and concluded it is "probably authentic."
Foreign Ministry spokesman Georg Schnetzer told the Austria Press Agency the tape appeared to have been made several weeks ago and contained scant information that might provide clues to the hostages' whereabouts.
"The tape is most probably authentic," yet contains no details on 25-year-old Bert Nussbaumer or the four Americans, Schnetzer told the agency.
Crescent Security Group, which employs the five men, became aware of a videotape and received the audio version on Wednesday, according to a statement on their Web site Thursday.
The statement also said the company would not be releasing the tape, the first proof that all five men are alive.
The men went missing Nov. 16 when a large convoy of trucks being escorted by Crescent Security Group was hijacked on a highway near Safwan, a city on the border with Kuwait.
Suspected militiamen dressed in Iraqi police uniforms ambushed the convoy, taking 14 hostages, including the five security guards, and nine truck drivers who were later released. The U.S. Embassy in Baghdad said this week it believes the five are still being held captive.
In the tape, Nussbaumer, speaking in English, gives his name, age and nationality and says he and his colleagues want "out of Iraq."
Video footage of the captives surfaced Tuesday, showing them to be alive and in good condition, according to McClatchy Newspapers.
Islamic Companies, a previously unknown group, claimed responsibility for the kidnapping, according to an Iranian-run Arabic-language satellite news station. It said the group released a videotaped message saying it was holding the five men and demanded the withdrawal of U.S. forces from Iraq and the release of all prisoners being held there.
Schnetzer said Austrian authorities were working "around the clock" to pinpoint Nussbauer's whereabouts and help gain his freedom.
Two of the American captives have also been identified: Jonathon Cote, 23, a native of Getzville, N.Y., and Paul Reuben, 39, a former police officer from a suburb of Minneapolis, Minn.