China will phase out service by substandard vessels on the main trunk of the Yangtze River over four years, starting on Oct. 1, a transport official said Thursday.

Substandard refers to environmental controls and to the ships' size and capacity, among other factors. Ships that are too small might not be able to navigate the river safely.

The move was intended to protect the environment, ensure safety in the reservoir areas of the Three Gorges and facilitate navigation of ships through the Three Gorges lock, Vice Minister of Transport Xu Zuyuan said in Hefei, capital of Anhui Province.

Substandard ships should be taken out of service on that part of the river or upgraded to meet Ministry of Transport (MOT) standards, Xu said.

Since the Three Gorges lock opened to trial navigation in June 2003, the MOT had issued 42 standards for ships in the Yangtze River, Xu said.

(Xinhua News Agency June 26, 2009)