Tajikistan has begun building what is expected to become the world's tallest dam. At a planned 335m tall (1,100 feet), Rogun would be higher than Jinping-1 Hydropower Station in China (305m), reports the BBC's Sohrab Zia.

Tajikistan, Central Asia's poorest country, has suffered from electricity shortages for years.

Rogun is meant to put an end to that, producing enough power to satisfy the country's energy needs with electricity to spare for export to Afghanistan and Pakistan.

The Rogun hydropower project will dam the Vakhsh river which flows through many steep gorges in the Pamirs, and managing its strength is one of the engineering challenges.

Guests at a ceremony inaugurating the project released doves in a gesture of peace. Tajikistan's downstream neighbours have been fiercely critical.

Uzbekistan and Kazakhstan fear that water could be diverted from their cotton and wheat fields. The Vakhsh is a major tributary to the Amu Darya river, one of the region's two major water courses. But a World Bank assessment gave the go-ahead two years ago.

Will Central Asia fight over water?

Tajik President Emomali Rahmon posed on a bulldozer he operated himself.

And posed with construction workers.

The Rogun hydropower project was first started 40 years ago. But the collapse of the Soviet Union, the Tajik civil war and problems in securing investments have delayed construction. Last summer Italy-based infrastructure company Salini Impregilo won the contract to complete the dam at a cost of $3.9bn.

When work is finished six giant turbines will produce electricity.

Workers will move millions of cubic metres of earth and rock as they build the dam.

Some electricity could flow from 2018, but it will take another seven and a half years for the dam to reach its full height, the contractors say.