Britain's outgoing ambassador in Baghdad has warned that civil war is the most likely outcome in Iraq, according to a report.
In a confidential memo to ministers, William Patey also predicted the break-up of Iraq along ethnic lines.
The assessment was contained in Mr Patey's final telegram from Baghdad before he left the Iraqi capital last week - details of which were obtained by the BBC.
The diplomatic cable was sent to the Prime Minister, Foreign Secretary, Defence Secretary, Leader of the House of Commons, and senior military commanders in both Iraq and the UK.
Mr Patey wrote: "The prospect of a low intensity civil war and a de facto division of Iraq is probably more likely at this stage than a successful and substantial transition to a stable democracy."
He went on: "Even the lowered expectation of President Bush for Iraq - a government that can sustain itself, defend itself and govern itself and is an ally in the war on terror - must remain in doubt."
But the memo also says that "the position is not hopeless, although it adds Iraq will remain "messy and difficult" for the next five to 10 years.
Talking about the Shiite militias blamed for many killings, Mr Patey says: "If we are to avoid a descent into civil war and anarchy then preventing the Jaish al Mahdi from developing into a state with a state, as Hezbollah has done in Lebanon, will be a priority."
The BBC reported it has also learned from military sources that British troops in Basra are planning to dramatically step-up operations against Shiite gunmen.
Mr Patey urges the Government to ensure that Iraqi troops are brought into this effort as the British forces "can't confront the militias alone".
Nevertheless, of the effort to hand over security duties to the Iraqis, he cautions: "Too much talk of an early exit from Iraq as this would "weaken our position".
The coalition aims to eventually hand over control to the Iraqi security forces.
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