"The Chinese revealed their plans for the water canal for the first time," he told reporters via video link from the capital of Astana, referring to the first round of bilateral talks on the issue held from May 5 to 15 in China.

Tokayev said the canal would siphon off around one billion cubic metres (35 billion cubic feet) of water a year from the Kazakh section of the Irtysh, or about 10 percent of the total flow.

Such volumes would not represent a major economic or environmental threat, he said.

The Irtysh supplies three hydro-electric power stations in the northeast of Kazakhstan and runs through some of the vast Central Asian state's industrial monoliths, including in Ust-Kamenogorsk and Pavlodar.

It eventually feeds into Russia's Ob river.

"It is in Russia's interests from an economic and political point of view to take part in these talks," Tokayev said.

Local experts have voiced concern about China's plans, saying that they could starve Kazakhstan enterprises of power as well as threaten vital shipping routes.

"If the water levels along the Irtysh begin to fall, then shipping could be interrupted," the state-owned Khabar news programme said this week.

"This is a worry not only for the Kazakh side, but also Russia, which is interested in having a normal shipping passage linking Ust-Kamenogorsk with Omsk."

Kazakhstan is extremely sensitive to suggestions that its relations with China, with which it shares a common border around 1,700 km (1,060 miles) long, are in any way strained.

The resource-rich steppeland state of 15 million feels vulnerable, wedged as it is between Russia to the north and China to the east. Since independence from Moscow it has worked hard to cement ties with both its mighty neighbours.

Tokayev stressed the importance of maintaining that stability, adding that neither China nor Kazakhstan should be tempted into meddling with each other's internal affairs.

Kazakh President Nursultan Nazarbayev looked to strengthen ties in 1997, selecting the state-run China National Petroleum Corp to invest $9.5 billion in the country's key oil sector in what he hailed the "contract of the century".

Key parts of that package of agreements remain stalled.