Nine people were killed when an American Black Hawk helicopter was shot down and crashed yesterday near the town of Fallujah, west of Baghdad just hours after a US military cargo jet came under missile fire over capital.
Both incidents underline that US forces in Iraq are still suffering significant losses despite the capture of Saddam Hussein last month.
A US military spokeswoman said: "A helicopter made an emergency landing near Fallujah. There were four passengers and four crew members on board and there are no survivors." She said she did not know if the helicopter had been hit by ground fire, and that it was on a medical evacuation mission when it came down.
Iraqi witnesses said the helicopter, which was marked with a red cross and flying in formation with a second Black Hawk, was brought down by hostile fire. The Pentagon said the transport plane which had to make an emergency landing came under hostile fire.
A few hours earlier, six mortar rounds exploded at a US army base, also just west of Baghdad, killing one soldier and wounding 34. The mortars, often used by the resistance, hit the sleeping quarters at Logistical Base Seitz.
The US army has been trying to bring down its casualties in Iraq after heavy losses in November. The number of US army patrols was cut from 1,500 a day in November to 500 a day in December. Checkpoints are mainly manned by Iraqi police.
While yesterday's attacks were taking place, a goodwill gesture by Paul Bremer, the chief US administrator in Iraq, was coming unstuck.
Mr Bremer had announced on Wednesday that 506 of the 12,800 Iraqis detained by the US would be released over the next few weeks, starting with 100 yesterday from the vast Abu Ghraib prison near Fallujah.
Relatives and friends of prisoners started gathering from 8am yesterday 200 yards from the main gate of Abu Ghraib. Rumours spread regularly that the release of prisoners was imminent. Hamid Obeid, whose brother Khalid was detained on 27 July, said: "First they told us it would be 10am, then 2pm, then 4pm." He said he had not seen his brother, a mukhtar (district leader), since he was arrested and did not know why he had been detained.
Many of the family members gathered outside Abu Ghraib agreed that they did not know the reasons for the arrests. Jamal, who spoke English and said he had a degree in civil engineering from Manchester University, claimed his brother Salah had been detained because neighbours with whom he was in dispute had "denounced him to the Americans as a terrorist". Only three of the Iraqis detained have been brought to trial.
As the hours passed with no releases it became clear that Mr Bremer's conciliatory gesture was becoming counter-effective. "I don't trust Americans. They are making more enemies for themselves now by arresting innocent people," said Jassim Rasheed. One man was shouting: "If the Americans do not release my cousin I will kill one of them."
The explanation for the failure of any released prisoners to appear finally emerged. Mr Bremer's office had failed to tell the US 800th Military Police Brigade, in charge of prisons in Iraq, to free any prisoners.
The release of those detained without trial has been a prime demand of Iraqi leaders. Adnan Pachachi, the head of the interim Iraqi Governing Council, had promised mass releases starting yesterday. But the cumbersome bureaucracy of Mr Bremer's administration seems to have ensured that his conciliatory action will do the US no good with Iraqis.