The Iraq conflict has wreaked "terrible damage" on the region - far more than has been acknowledged, the Archbishop of Canterbury has said.
Dr Williams' comments followed a visit to Iraqi refugees in Syria
Dr Rowan Williams said "urgent attention" was needed to stabilise the country. His comments followed a visit to Syria to meet Iraqi refugees.
The Foreign Office said it backed the Iraqi government's security efforts.
A survey published in September 2007 suggested that up to 1.2m people might have died because of the Iraq conflict.
Speaking following his visit, Dr Williams also said he regards any further "deliberate destabilisation" of the region - such as action against Syria and Iran - as "criminal, ignorant...and potentially murderous folly".
Referring to US political advisers, he added that "we do hear talk from some quarters of action against Syria, or against Iran".
"I can't understand what planet such persons are living on when you see the conditions that are already there. The region is still a tinderbox," Dr Williams said.
Earlier, the archbishop said "events of the last few years have done terrible damage in the whole of this region".
He said many people "do not see the cost in human terms of the war which was unleashed".
Dr Williams concluded: "Security that will enable these people to return to Iraq depends on a settlement for the whole of that country guaranteeing the liberty and dignity of every minority."
Following the archbishop's comments, the Foreign Office said it continued to support the Iraqi government "in aiming to bring support to the country", adding that "there are signs this is having some effects".
A spokesman said: "The American surge has had its effect and we have noticed there has been a reduction in violence in Basra at the moment.
"Our support of the Iraqi government will continue. Their security forces are getting better and better. We will keep that support going by mentoring and continuing to train them."
About half a million refugees have fled Iraq for Syria since the conflict began in 2003.
Dr Williams said many of the people he had met told him they left the war-torn country because their families had been kidnapped, executed or told they would be killed unless they paid ransoms.
The archbishop added that the refugees had told him their circumstances were desperate and unsustainable, with no hope either of a safe return to Iraq or of citizenship in Syria or elsewhere.