Central Asia welcomed China's foray into their energy-rich region on Sunday as Chinese leader Hu Jintao prepared to open a new pipeline connecting a Turkmen gas field with China's restive Xinjiang region.

Leaders of Kazakhstan, Uzbekistan and Turkmenistan assembled in the Turkmen capital Ashgabat on Sunday to greet Hu on the eve of a ceremony to commission the 1,833km(1,139-mile) pipeline that snakes across Central Asia via their countries.

The pipeline marks a new stage in China's involvement in the former Soviet region and represents a snub to Russia which still sees the Muslim region as part of its sphere of influence.

Central Asia's overtures towards China also represent a worry for the European Union which sees gas-rich Turkmenistan as a potential new supplier of gas for the Nabucco project designed to connect Europe with Caspian gas field while bypassing Russia.

Speaking in Ashgabat, a city of marble palaces tucked away in a desert near the Iranian border, Hu described Turkmen President Kurbanguly Berdymukhamedov as an "old friend".

"Your sense of importance towards China and your efficiency have really impressed me," said Hu. "You and I will will soon open the Central Asia-China pipeline...It's a momentous event."

Speaking later, Berdymukhamedov, a former dentist who came to power in 2007 after the death of his secretive and autocratic predecessor, praised China's commitment to Central Asia.

"This project has not only commercial or economic value. It is also political... China, through its wise and long-sighted policy has become one of the key guarantors of global security."

The China pipeline, starting near a Turkmen gas field developed by CNPC, is Central Asia's biggest export route to markets outside Russia, and fully bypasses it territory.

With capacity of 40 billion cubic metres a year, it will ease Turkmenistan's reliance on Russia, which purchased about 50 bcm a year before the two fell out over supply terms this year.

The pipeline is expected to reach full capacity in 2012-13.

Hu's visit serves as a rare unifying force for regional leaders who, ridden by rivalries and rows over cross border water and electricity use, rarely meet to discuss matters.

Their willingness to put side their differences and fly to Turkmenistan's remote capital to meet Hu shows their resolve to forge closer ties with their giant eastern neighbour.

Speaking ahead of Hu's arrival, Uzbek president Islam Karimov โ€” who rarely goes abroad or speaks in public โ€” said the pipeline was a key step towards diversifying energy exports.

"The geopolitical map is changing... and Turkmenistan''s role will only grow," said Karimov, who has ruled Uzbekistan since 1989.

Central Asia, home to some of the world's biggest oil, gas and metals reserves, is at the centre of a geopolitical tug-of-war between Russia, China and the West, all seeking to grab a share of its untapped riches.

Years of quiet diplomatic manoeuvering have helped China step up its presence in the region by handing out billions of dollars in loans, snapping up energy assets and building an oil pipeline from Kazakhstan.

"We are ready for cooperation in exploration, gas processing and maintenance of deposits," Hu said in Ashgabat. "We have proposals on reconstruction of refineries... in the transport, telecoms and construction sectors."

In Kazakhstan on Saturday, Hu and his delegation signed a range of investment deals, most detailing earlier agreements between Astana and Beijing, in sectors such as steel, chemicals, renewable energy and reconstruction of a Kazakh oil refinery.

Russia's Gazprom stopped buying Turkmen gas in April after a pipeline explosion sparked a broader diplomatic row over gas. The move has cost Turkmenistan about $1 billion a month and prompted it to forge closer ties with other nations.

As diplomacy heats up, Russian President Dmitry Medvedev is due to travel to Turkmenistan later this month for energy talks.