Newly released Ministry of Defence documents state that:

� The arrests took place in waters that are not internationally agreed as Iraqi;

� The coalition unilaterally designated a dividing line between Iraqi and Iranian waters in the Gulf without telling Iran where it was;

� The Iranian Revolutionary Guards� coastal protection vessels were crossing this invisible line at a rate of three times a week; It was the British who apparently raised their weapons first before the Iranian gunboats came alongside;

� The cornered British, surrounded by heavily armed Iranians, made a hopeless last-minute radio plea for a helicopter to come back and provide air cover.

Iran always claimed that it had arrested the Britons for violating its territorial integrity.

Des Browne, the Defence Secretary, repeatedly told the Commons that the personnel were seized in Iraqi waters.

The MoD, in a televised briefing by Vice-Admiral Charles Style, the Deputy Chief of the Defence Staff, produced a map showing a line in the sea called �Iraq/Iran Territorial Water Boundary�. A location was given for the capture of the Britons inside what the chart said were �Iraq territorial waters�. But the newly released top-level internal briefing accepts that no such border exists.

The report, addressed to Air Chief Marshal Sir Jock Stirrup, the Chief of the Defence Staff, blames the incident on the absence of an agreed boundary and a failure to coordinate between Iraq, Iran and the coalition.

Under the heading �Why the incident occurred�, the report examines the history of a border that has been disputed since a treaty between the Persian and Ottoman empires in 1639.

Professor Robert Springborg, of the School of Oriental and African Studies, said yesterday that it was negligent to fail to clarify with the Iranians where the notional boundary was.

Using the Freedom of Information Act, The Times made requests about the events. The MoD released two documents, although parts are censored. One is the report to Sir Jock dated April 13, 2007, a week after the Britons returned home unharmed. It was compiled after they had been debriefed. The other is the communications log between the mother ship HMS Cornwall and the two seaboats used by the boarding party.

What they said

�There is no doubt that HMS Cornwall was operating in Iraqi waters and that the incident itself took place in Iraqi waters . . . In the early days the Iranians provided us with a set of coordinates, and asserted that was where the event took place, but when we told them the coordinates were in Iraqi waters they changed that set and found one in their own waters. I do not think that even they sustain the position that the incident took place anywhere other than in Iraqi waters�

Des Browne, Defence Secretary, House of Commons, June 16, 2007

�Since the outset of the Iraq-Iran War there has been no formal ratified TTW [territorial waters] agreement in force between Iraq and Iran . . . In the absence of any formal agreement, the coalition tactical demarcation (the Op Line) is used as a notional TTW boundary. It is a US NAVCENT [US Naval Forces Central Command] construct based on an extension of the Algiers accord demarcation line beyond the mouth of the Shatt al-Arab [waterway] into the NAG [northern Arabian Gulf]. While it may be assumed that the Iranians must be aware of some form of operational boundary, the exact coordinates to the Op Line have not been published to Iran.�

MoD report to the Chief of the Defence Staff under the heading: �Why the incident occurred�, dated April 13, 2007, released to The Times under the FoI