GCC oil producers have started work on more than $1 trillion of real estate projects as they spend windfall energy-export revenues on malls, office towers and theme parks, a Dubai-based consultancy said.

There are 885 active building sites in Saudi Arabia and its five Gulf neighbours, each with a value of at least $10 million, Proleads said in a statement. The largest five projects had a combined value of $358 billion, it said.

The survey covered commercial and residential developments including hotels, hospitals, schools and theme parks. If infrastructure such as bridges, roads and airports were included the value of projects would be $1.25 trillion, Proleads said.

With oil prices quadrupling since 2002 to a record high just $90 a barrel, governments are investing their windfall to reduce reliance on energy exports by developing tourism, financial services and industry.

Proleads estimated that the largest project, King Abdullah Economic City in Saudi Arabia, was worth $120 billion.

The government initially valued the project, which will include a port and financial district on the Red Sea Coast, at more than $26 billion. It said last year it would triple the area under development to 168 million sq m (1.808 billion sq ft).

The six countries were investing a combined $81 billion in residential real estate projects and a $190 billion in hotels, according to Proleads.

The UAE, Kuwait, Qatar, Oman and Bahrain were the other countries covered by the survey, it said.Reuters