Both of the Puma helicopters involved in the incident were from RAF Benson, Oxfordshire. Of the two individuals killed in the incident, one was from the Royal Air Force, a member of the crew - a loadmaster, and the other from the Army.
In a statement, Defence Secretary Des Browne said:
"I have been deeply saddened by the loss of two of our brave Service personnel in northern Iraq earlier today. Each tragic incident of this type is another reminder of the daily risks that our servicemen and women face in the course of their important duties.
"The Puma helicopters were taking part in a routine operational flight north of Baghdad. The reports that I have received indicate that the crash was an accident and not as a result of an attack.
"To date Puma helicopters have had a very good safety record, however the precise cause will be subject to an investigation.
"Although both helicopters have been damaged we intend to recover both of them. I am grateful to the US forces who were able to seal off the area quickly.
"The six casualties were all from the same helicopter. Of the individuals killed in the incident, one was from the Royal Air Force, the other from the Army.
"Of the four personnel injured in the crash, two have now been discharged back to their units. The other two, including one who is very seriously injured, are receiving medical attention at a US hospital.
"Our focus here in the UK is on providing the families with support at this extremely difficult time. Our thoughts are with them tonight."