US soldiers looking for a German woman and her son being held hostage by an Iraqi Islamist group raided houses in Baghdad last night.
The troops had been acting on a tip-off but failed to find the Hannelore Marianne Krause and her son.
Ms Krause is married to an Iraqi doctor and moved to Iraq 40 years ago. Her son is reported to be in his mid-20s and has dual German-Iraqi citizenship.
A little-known group, the Arrows of Righteousness, has threatened to kill the two hostages unless Germany withdraws its 3,000 troops from Afghanistan. The two were seized from their home in the western Baghdad district of Ghazaliya early last month.
The kidnappers released a video a few weeks ago showing Ms Krause weeping with her son and appealing to German Chancellor Angela Merkel to meet the kidnappers' demands.
Germany, which opposed the 2003 US-led invasion of Iraq, has around 3,000 troops in Afghanistan as part of a Nato force stationed there since US-led troops toppled the Taliban in 2001.
The German government has said it is working to try to secure the hostages' release but will not be blackmailed.
Last year two German engineers were captured in Iraq and held for 99 days before they were freed. It is not clear if a ransom was paid.