Bangkok, Oct 10 (IANS): Thai authorities Monday confirmed that all 13 Chinese crewmen on two hijacked ships were killed last week.

Investigators suspect that a drug ring of Shan, or Tai Yai, ethnic group led by Nor Kham was responsible for the killings, Seramsak Seesan, an official, told Xinhua.

Maj Gen Prakarn Chonlayuth, commander of the Pa Muang Task Force, Thailand's border army, said the Nor Kham drugs gang killed all the crew members of any vessel which refused to pay the gang protection money.

Nor Kham, 40, wanted for drugs trafficking, had expanded his illegal activities to collect protection money from Chinese-flagged cargo ships a few years ago, Prakarn said.

The gang hijacked ships plying the river and demanded protection money from them. If they refused to pay, they would kill the crew and take over the ships to deliver drugs from Myanmar to Thailand, he added.

About 400 armed men are thought to belong to the Nor Kham drugs gang, said Permpong Chavalit, another official.

Searchers found the body of the last Chinese crewman in Chiang Khong district early Monday.

Last Wednesday, Thai border troops seized drugs on board two Chinese-flagged ships coded Yi Xing 8 Hao and Hua Ping, after a gunfight of more than 30 minutes with drug traffickers, in Chiang Saen district, bordering Myanmar. One drug trafficker was reported to have been killed.

The police found bodies of the Chinese sailors late last week. Three bodies, with hands tied and handcuffed behind their backs, were found Friday. Another nine bodies were found Saturday.

The bodies were identified as the crew of Yu Xing 8 Hao and Hua Ping. The police suspected that drug traffickers had planned to use the hijacked ships to smuggle drugs into Thailand and the sailors were killed before the gunfight Wednesday.