Poor urban infrastructure and high youth unemployment helped fuel the Arab Spring and governments across the region must tackle both if they are to prevent further unrest, the United Nations said in a report on Monday.

The urban population of Arab cities is expected to more than double to 438.6 million by 2050, increasing demand for housing, social services and infrastructure, the UN Human Settlements Programme (UN Habitat) said.

Although the primary trigger for unrest across the region in the past year appeared to be a desire for more freedom in the face of entrenched autocracies, the report said social factors had intensified people's frustration and would need to be addressed along with their political concerns.   

"What is often less understood is that the Arab Spring is really a call for social reform and urban policies that can deliver adequate living conditions for rapidly growing young and poor urbanites," UN Habitat said at the launch of its 'State of Arab Cities 2012' report in Kuwait.

"Youth employment is very high in the Arab region and the chances of finding affordable housing is a dim prospect for many urban youths too," it said. "These two trends converge in Arab cities in an explosive mixture that has fuelled the region's social unrest over the past year."

The revolts that erupted last year have toppled Arab autocrats in Tunisia, Egypt, Libya and Yemen, are still raging in Syria, and have sent shockwaves across the whole region. The trigger was the self-immolation of a young Tunisian vegetable seller, an act of protest against poverty and official repression.

The United Nations noted that the uprisings were mostly an urban phenomenon and that cities across the region became meeting grounds for citizens demanding better governance, economic management and transparency.

"Too many Arab societies continue to suffer under unacceptably high levels of urban poverty and under-development while, at the same time, urban innovations are being introduced with dazzling speed in others," it said in a separate statement.

Around 60 percent of the region's population is under 25 and overall unemployment rates range from 11 percent in Kuwait to 35 percent in Morocco, the agency added.

It criticised hugely complex urban governance systems and authorities' disregard for sustainable town planning. Even in richer countries like Kuwait and other Gulf states, meagre water resources pose a serious risk to food supply, health and economic development, it said.

"Currently available groundwater reserves are being depleted at alarming rates," it said, describing the Gulf as one of the world's most water-scarce areas with the region's most rapid population growth.

Five Gulf countries rank among the world's ten countries with the lowest per capita renewable water resources, it said, adding that low tariffs have discouraged water conservation.  "This trend of increasing demand and decreasing supply is unsustainable and will start to affect population health and economic development."     

It cited Yemen as the country most vulnerable to water shortages and said the capital Sanaa would run out of supplies within 10 to 15 years. - Reuters