Energy-rich Turkmenistan signed a deal to boost its annual delivery of natural gas supplies to China to 40 billion cubic meters, an increase of 10 billion cubic meters over the previously agreed amount.

Under the deal Friday, China could start receiving gas deliveries from the Central Asian nation by late 2009.

Construction of a pipeline that is meant to eventually stretch from Turkmenistan to China''s northwestern Xinjiang region via Uzbekistan and Kazakhstan is slated for completion next year.

Chinese premier Hu Jintao visited Turkmenistan to seal the agreement with his Turkmen counterpart, Gurbanguly Berdymukhamedov, at a ceremony in the capital.

"Our joint efforts are clearly visible in the transnational pipeline joining Turkmenistan with China along the banks of the Amu Darya river, where Turkmen specialists have discovered a gigantic oil and gas field," Berdymukhamedov said.

Hu said every effort would be made to speed up the pace of construction work on the pipeline.