Doha (AFP) - Gas-rich Qatar signed a $470-million deal on Sunday to build its first solar energy plant, capable of meeting up to one-tenth of peak national power demand.

The Al-Kharsaah plant, near the capital, is a 10-square-kilometre (4-sq-mile) joint venture with French and Japanese partners due for completion in 2022 ahead of the football World Cup.

"Eight times the solar power pledged in the World Cup bid will be produced," Energy Minister Saad al-Kaabi told a media briefing in Doha.

Qatar's ruler, Emir Sheikh Tamim bin Hamad Al-Thani, vowed at the United Nations last year that the tournament would be carbon neutral, but gave little detail on how this would be achieved.

"Production capacity will be around 800 megawatts and 10 percent of peak demand," said Kaabi following a signing ceremony between Qatari state firms, France's Total and Japan's Marubeni.

"Eight-hundred megawatts will be the largest (solar power plant) built by Total," said the French energy giant's chief executive, Patrick Pouyanne.

By contrast, Abu Dhabi's Sweihan plant, one of the world's largest solar projects, produces 1,177 megawatts.

The capital cost of the venture is 1.7 billion riyals ($470 million), Kaabi said, with state firms taking a 60-percent stake and foreign investors 40 percent.

Marubeni will take 51 percent of the minority holding, while Total will have 49 percent.

"It's a pilot project, you have to assess how successful it is," added Kaabi.

Gulf states, heavily depend on oil and gas, have invested tens of billions of dollars in clean energy projects, mainly in solar and nuclear.

But critics say many such projects are slow to get off the drawing board.

The United Arab Emirates said last week its first nuclear power plant would start operating within months after repeated delays to meet safety and regulatory conditions.

The UAE will have the first operational nuclear reactor in the Arab world.

Saudi Arabia, the world's top crude oil exporter, has said it plans to build up to 16 nuclear reactors, but the projects have yet to materialise.

Critics say the addiction to oil is hard to kick, particularly when supplies remain abundant and the high costs of investment in infrastructure needed to switch to renewables.