Officials say a civilian tip led to the arrests during overnight raids of two houses. Bomb-making material also was confiscated. The military did not say where the houses were located nor did it give the suspects' nationalities.
The civilian helicopter was shot down about 20 kilometers north of Baghdad Thursday. Two militant groups have claimed responsibility for the attack and have released video footage of it.
Meanwhile, two separate car bomb explosions in Baghdad today (Saturday) killed nine Iraqi soldiers and one civilian. More than 30 other people were hurt, including three American soldiers.
And to the south, near Basra, a car exploded, killing its two passengers and wounding two Iraqis.