Eleven Chinese were killed and two missing after their cargo boats were attacked in the golden triangle area of the Mekong River, state media said on Sunday.

The two ships, the Hua Ping and Yu Xing 8, were attacked on October 5, according to the Xinhua news agency, which said China's leaders were "paying close attention to the matter".

The foreign ministry in Beijing has asked the Chinese embassy in Thailand and consulate general in the northern Thai city of Chiang Mai to investigate and do all they can to find the missing crewmen, Xinhua said.

Beijing had also asked "relevant countries" to take measures to improve the protection of Chinese ships and sailors in the Mekong River, the report said, quoting a statement on the ministry's website.

The Mekong River region comprises Cambodia, Laos, Myanmar, Thailand, Vietnam and China's Yunnan Province.