Russian officials say three Russian and five Ukrainian engineers taken hostage by insurgents in Iraq have all been released.
An uneasy ceasefire is holding in Falluja
The workers for a Russian energy company were in Baghdad to repair power stations when they were abducted.
In another development, US troops have arrested a senior aide to radical Shia cleric Moqtada Sadr.
Further clashes between US forces and Sunni insurgents have been reported near the flashpoint town of Falluja.
A US Apache helicopter crashed between Falluja and Abu Ghraib after being hit by a rocket, witnesses said.
The incident came after US helicopters reportedly fired missiles at targets in the nearby town of al-Karma.
However, a fragile truce in Falluja itself appears to be holding.
In other developments on Tuesday:
- A bomb attack on a US convoy travelling from Baquba to Najaf killed one soldier and wounded another, as well as a civilian contractor, the US military said
- One Ukrainian soldier was killed and several others wounded in an incident in Iraq, said the Russian Itar-Tass news agency, which gave no further details
- Russia's biggest contractor in Iraq, Tekhpromexport, is pulling out its 370 staff from Iraq because of the spate of kidnappings of foreigners
The Russians and Ukrainians had formed the biggest contingent of foreign hostages in Iraq, following the release of seven Chinese men seized on Sunday near Falluja.
They were abducted when armed men in masks burst into their home in a suburb of Baghdad on Monday evening.
Nine engineers were seized and driven away - one was later released.
There are reports that two Iraqi guards may have been killed during the abduction.
An official from their company, Interenergoservis, told Russia's Ria news agency that the engineers were freed once their kidnappers realised their nationalities.
Two of the Chinese were injured during the kidnapping
The official said the abductors apologised to their hostages, who were then put in a taxi and driven home.
A number of other foreigners have been taken hostage or reported missing in Iraq, including three Japanese citizens abducted last Thursday whose fate remains unknown.
Their captors had threatened to burn them alive unless Japan withdrew its 550 troops from Iraq - but the 11 April deadline has passed without any news of their fate.
Three Czech television journalists were also taken hostage north of Baghdad on Monday morning.
Iraqi security forces have taken control of the southern city of Najaf, after armed Shia militiamen loyal to Mr Sadr withdrew from police stations and government buildings in the city.
The whereabouts of Mr Sadr, who has refused to dissolve his Mehdi Army militia, are unclear.
The senior US military commander in Iraq, Lt Gen Ricardo Sanchez, has said it is an American objective to kill or capture him.
An aide to Mr Sadr, Hazem al-Araji, has been detained in Baghdad. Witnesses said he was arrested after being interviewed by Italian journalists at a hotel, and was driven away in a US armoured vehicle.
US military commanders in Iraq have asked for more combat troops
The earlier arrest of another aide to Mr Sadr sparked off the current Shia unrest.
As the kidnap dramas continued to unfold, US military commanders in Iraq asked for two more brigades of mobile combat troops to deal with the volatile situation on the ground.
"In terms of capability, what I have asked for is essentially to have a strong mobile combat arms capability," the head of US Central Command, Gen John Abizaid, said.
"We're working [out] the details with the joint staff as far as the sourcing is concerned. I really don't have the precise answer as to who and how that'll be filled right now."
Gen Abizaid also told reporters that the return of some troops from Iraq to the US would almost certainly be delayed.