The Central Asian state of Turkmenistan has undertaken to deliver 30 billion cubic metres of natural gas to China every year starting from 2009, the official Neutral Turkmenistan daily said Tuesday.

"The Chinese side will buy natural gas from the Turkmen side … at a volume of 30 billion cubic metres (1.1 trillion cubic feet) for a period of 30 years," the newspaper said.

Neutral Turkmenistan published a copy of the agreement signed on Monday in Beijing between Chinese President Hu Jintao and his Turkmen counterpart Saparmurat Niyazov.

The document foresees the construction of a gas pipeline between the two countries by 2009.

Further talks are set to take place before the end of the year on details for the development and construction of the pipeline, the newspaper said.

A similar project was announced in 1998 but construction on the 8,000-kilometre pipeline from a budget of between eight and 11 billion dollars never got off the ground.

China, whose rapidly growing economy needs increasing amounts of energy, is seeking to diversify its supplies of oil and gas. Last month, Russian President Vladimir Putin announced Russia would build two gas pipelines to China.

Meanwhile in other China-Turkmenistan news, the Chinese President Hu Jintao and his Turkmenistan counterpart Saparmurat Niyazov have agreed on the need to crack down on restive Muslims inhabiting northwest China, state media said Tuesday.

The two leaders had agreed late Monday in a joint statement on security to rein in "separatist forces of 'East Turkmenistan'," Xinhua news agency reported, without giving any details.

"East Turkmenistan" is the name used by some pro-independence groups for Xinjiang, a vast desert region on China's border with Central Asia whose people are mostly Muslims.

"Terrorism, splittism and extremism pose a grave threat to the security and stability in the region," Xinhua quoted the statement as saying.

The largest ethnic group in Xinjiang are Uighurs, speakers of a Turkic language who hoped in the early part of the 1990s to get more backing from people of the same ethnicity in Central Asia.

One of China's main objectives in stepping up links with Central Asia's republics is to ensure that such cross-border cooperation does not happen.

Niyazov, Turkmenistan's president-for-life, arrived in China on Sunday for a six day state visit that will also include stops in China's economic hub Shanghai and the eastern province of Zhejiang.