The kidnappers, a group called Ansar al-Tawheed wal Sunna (Followers of Unity and Prophetic Tradition), demanded the release of all Iraqis held in US-run prisons and told Germany to stop giving help to the US and Iraqi authorities.

Chancellor Angela Merkel said her government was scrutinizing the video of engineers Thomas Nitzschke, 28, and Rene Bräunlich, 32, which was posted on an Islamic Internet site on Sunday.

"We are closely scrutinizing the video we have received of the hostages," Merkel said, adding: "We will do everything in our power to save the hostages and to bring them back to Germany."

In the 24-second video, dated March 28, Nitzschke pleads with the German government to save him and Bräunlich.

"Breaking point"

"We have been held captive here for more than 60 days. We are close to breaking point. Please help us. Please help us," he said.

The video shows the two hostages looking haggard and wearing beards.

In an accompanying statement the kidnappers threatened: "Know that if our two demands -- the release of all Iraqi men and women held in occupation prisons and a halt to all aid to Americans and their agents, including Shiites -- are not met, punishment will be meted out quickly.

"Those of you who help the occupiers, the infidels and the Shiites, know that you and your citizens will not escape the jihadists (holy warriors)."

The German foreign ministry said it was analyzing the video to confirm that it indeed featured the two Germans who were seized near the Baiji oil refinery in northern Iraq on January 24.

"We still have to analyze the video," a spokeswoman told AFP.

Previous videos

Germans have for weeks feared for the lives of the two men, who both come from Leipzig, in the east of the country. They were working for a German company on short-term contracts when they were seized.

Their captors have previously released three videos of them, the first just three days after they were taken hostage. The second was shown on the Arabic television channel Al-Jazeera on Jan. 31.

In it the kidnappers threatened to kill the hostages within 72 hours unless Berlin closed its embassy in Baghdad and ended cooperation with the Iraq government. They also demanded that all German companies withdraw from Iraq.

The most recent video was aired by Al-Arabiya news channel on Feb. 13 and showed the hostages kneeling in front of men wearing hoods and brandishing automatic weapons.

ARD television in late March said the German government had received indications that the men were still alive but had failed to establish direct contact with the kidnappers. The television channel cited unnamed government sources as saying the captors were demanding a ransom.

Residents of Leipzig have been holding candle-lit vigils for the men at the beginning of every week. They said they would hold the 21st vigil on Monday in the city's Nicholas Church and pray for their safe release.