FRANKFURT (Reuters) - Desertec, the world's most ambitious solar power project, is to start building its first power plant next year, a 500 megawatt (MW) facility in Morocco costing up to 2 billion euros ($2.8 billion), the project lead told a German newspaper.

"Construction is to start in 2012," Ernst Rauch of Munich Re, initiator of the Desertec Industrial Initiative (DII), told Sueddeutsche Zeitung in an interview published on Saturday.

Founded by mostly German companies in 2009, the 400 billion euro Desertec project will use mirrors to harness the sun's rays to produce steam and drive turbines for electricity generation in the Sahara region within the next decade.

The first phase of the 12-square-kilometre Moroccan complex will be a 150 MW facility costing up to 600 million euros that will take two to four years to build, the newspaper said.

"Depending on the technology, electricity production can start in 2014, or no later than 2016," Rauch said, adding details of the project in Morocco -- such as location, technology, and financing -- should be agreed by early 2012.

DII's goal is to analyze how to develop clean energy in the North Africa deserts that could supply up to 15 percent of Europe's power demand by 2050. Deserts get more energy in six hours than the world's population consumes in a year, DII says.

Fields of mirrors in the desert would gather solar rays from concentrated solar power (CSP) to boil water, turning turbines to electrify a new carbon-free network linking Europe, the Middle East and North Africa.

DII is a product of the Desertec Foundation, a global network of governments, companies and think tanks that is exploring how to harness solar power in deserts.

The DII project has a range of corporate backers from the energy, technology and construction sectors as well as banks and a reinsurer. Shareholders include ABB, Munich Re, Abengoa, Deutsche Bank, RWE, Enel, Saint-Gobain, E.ON, HSH Nordbank, Siemens and Red Electrica.

(Reporting by Maria Sheahan)