Upheaval in the Middle East and Islamic civilisation could cause another world war, the US ambassador to the UN was quoted as saying in an Austrian newspaper interview.

Zalmay Khalilzad told the daily Die Presse the Middle East was now so disordered that it had the potential to inflame the world as Europe did during the first half of the 20th century.

'The (Middle East) is going through a very difficult transformation phase. That has strengthened extremism and creates a breeding ground for terrorism,' he said in remarks translated by Reuters into English from the published German version.

'Europe was just as dysfunctional for a while. And some of its wars became world wars. Now the problems of the Middle East and Islamic civilisation have the same potential to engulf the world,' he was quoted as saying.

Khalilzad, interviewed by Die Presse while attending a foreign policy seminar in the Austrian Alps, said the Islamic world would eventually join the international mainstream but this would take some time.

'They started late. They don't have a consensus on their concept. Some believe they should return to the time (6th-7th century) of the Prophet Mohammad,' he was quoted as saying.

'It may take decades before some understand that they can remain Muslims and simultaneously join the modern world.'

Khalilzad was also quoted as saying Iraq would need foreign forces for security for a long time to come.

'Iraq will not be in a position to stand on its own feet for a longer period,' he said in the interview.

Asked whether that could be 10-20 years, he said: 'Yes, indeed, it could last that long. What form the help takes will depend a lot on the Iraqis. Up to now there is no accord between Iraq and the US about a longer military presence.'

Khalilzad said the chaos in Iraq since US-led forces overthrew Saddam Hussein in 2003 was not unavoidable but arose from mistakes in the initial period of occupation.

'Historians are discussing now whether we should have sent more troops to Iraq to preserve law and order, if it was right to dissolve the Iraqi army, if we should have built an Iraqi government quicker, if there should have been such a sweeping de-Baathification programme (removing Saddam-era officials).' Reuters