Chinese President Xi Jinping and his Tajik counterpart Emomali Rakhmon witnessed the start of the China-Central Asia gas pipeline's Line D construction in Tajikistan on Saturday, which marks a big step of another important energy channel for the world's second largest economy.

Xi said the strategic China-Central Asia gas pipeline project will significantly boost the regional economic development during the ceremony.

At present, China has three natural gas pipelines which connect with Central Asian countries.

The 1,000-km Line D is the fourth with 410 km in the territory of Tajikistan.

It will run through Uzbekistan, Tajikistan and Kyrgyzstan, to deliver gas from Turkmenistan to China.

The designed delivery capacity of Line D is 30 billion cubic meters annually.

Combined with the other three pipelines named Line A, B and C, China will have a total imported natural gas capacity of 85 billion cubic meters annually from Central Asian countries.

The current three pipeline network passes through Uzbekistan and Kazakhstan and then arrives at China's western Xinjiang Uygur autonomous region.

China imported 53 billion cubic meters of natural gas last year, 25 percent increase year-on-year, according to China National Petroleum Corporation, the country's state-owned energy giant.

As the government encourages clean energy consumption to cut carbon emission in China, the natural gas consumption is expected to keep growing.

The Central Asian gas-rich countries have been increasing their supply to China.

By the end of China's 13th Five Year Plan in 2020, all four lines of China-Central Asia gas pipeline network will be able to supply China with 80 billion cubic meters a year, accounting for at least 40 percent of China's total imported gas supplies by then, according to CNPC.

On Saturday, Xi also presented the starting ceremony of the second phrase of Dushanbe power station.

To ease the power shortage problem, Tajik government signed agreement in 2009 with China's Xinjiang Tebian Electric Apparatus Stock Co for two thermal power stations located in its capital city.

The first phrase of the power station project was completed in August and the second phrase started construction on Saturday when Xi said the project symbolizes the friendship between people from the two countries.

The first phrase provides one third of the electricity consumption and winter heating in Dushanbe. The entire power station project will be able to supply winter heating for the whole city after the completion of the second phrase.