BEIJING - China has successfully developed its largest rocket propellant tank, which will be used to contain hydrogen fuel for the country's Long March-5 carrier rocket, the tank's developer said Wednesday.

The homegrown rocket tank, measuring five meters in diameter and 20-plus meters in length, consists of bottom parts and eight tubular sections, which are welded together, according to the China Academy of Launch Vehicle Technology.

The academy made a major technological breakthrough in the welding of such a massive-sized fuel tank, it said, adding that developing and manufacturing a propellant tank are among the most difficult tasks in building a rocket.

According to a government white paper issued last month, China will develop next-generation launch vehicles, including Long March-5, Long March-6 and Long March-7, in the 2011-2015 period.

The Long March-5 will use a non-toxic and pollution-free propellant, and will be capable of placing a 25-tonne payload into near-Earth orbit, or placing a 14-tonne payload into geostationary orbit, the paper said.