A former senior PSNI officer who served as a police advisor in Iraq, has told the Chilcott Inquiry he felt isolated and unsupported much of the time there.
Former Assistant Chief Constable Stephen White will appear as a witness to the inquiry on Wednesday but has already supplied his statement.
Although he signed up for a posting to Basra of two to three years, he left after six months.
He said a lack of resources and information contributed to this.
"I reflect on my time there with some sadness and much frustration," he said.
"I truly believe that there was a wasted opportunity, soon after the removal of Saddam Hussein and his regime, for 'the West' and in particular UK policing, to provide much needed support to the liberated country, specifically its four southern provinces."
Mr White served as senior police adviser and director of law and order for southern Iraq between July 2003 and January 2004.
He said it became very clear from his first day in Basra that the military in the south of Iraq saw him as their relief from all law and order reform duties, not just police reform.
"This expectation was to become very evident and the cause of much tension throughout my tour of duty," he said.
"My main thought after less than one day in country was about the 'disconnect' between London and Basra even in simple matters."
He said later in his tour he would be embarrassed daily whenever senior military colleagues asked "when 'we' would relieve them of some policing tasks".
He said he became extremely frustrated that he was not supported in terms of equipment, expertise and personnel.
His statement also mentions seeing a Bosnia police training curricula in Baghdad with the word Bosnia struck out and Iraq written on it.
Mr White was forced to work with a team of just eight officers for five of the months he served in Iraq, which he said would have been almost laughable had it not been so serious.
During his deployment, Mr White was a subject of a BBC NI Spotlight documentary on his work in southern Iraq.
He said his "perhaps, too honest" responses to some questions caused some controversy but may also have finally prompted some action to be taken to help him.
Mr White said it was only after meeting Foreign Secretary Jack Straw face-to-face near the end on November 2003 "that I genuinely felt for the first time that the professional expertise which I had been asked to bring to Iraq was valued and that my advice was being listened to - by the right person".
"I was shocked when he told me that he was being told that there were no delays in getting police out to Basra," he said.
"I believed at the time and still do that it was only after the foreign secretary had been to Basra and allowed me to brief him personally that any tangible support in the shape of certainty about resources which then started to arrive a few weeks later."