Uzbekistan on Thursday warned Tajikistan not to move ahead with the construction of a controversial hydro-electric dam that has severely strained relations between the two Central Asian states.

Uzbek Prime Minister Shavkat Mirziyayev, in a letter to his Tajik counterpart, demanded an independent examination of the possible consequences of the massive Rogun dam before Dushanbe begins construction.

Tashkent fears the dam will damage its vital cotton industry, which depends on water which flows in from Tajikistan and Kyrgyzstan, and negatively impact the environment of millions of Uzbeks living downstream, Mirziyayev said.

"Uzbekistan's fundamental position on this issue is to move ahead with the construction of Rogun station only after a thorough independent analysis of the project," he said in a letter published by the official UzA news agency.

He also warned that Uzbekistan would seek the assistance of the international community to back its position.

The letter highlights the increasingly tense relations between the two Central Asian states, which have been at odds on a number of issues for almost two decades since the collapse of the Soviet Union.

The Rogun dam, which was first conceived as a gigantic Soviet hydro-electric power project, stalled as Tajikistan plunged into civil war in the early 1990s after the breakup of the USSR.

Mountainous Tajikistan, the poorest of the ex-Soviet republics of Central Asia, sees Rogun as a means of solving its chronic energy shortages while at the same time allowing it to become a net exporter of electricity.

Last month Dushanbe began a new drive to raise funds for the dam, a mass share sale in a drive to raise 1.4 billion dollars to complete the languishing project.