Chinese and Thai authorities will closely cooperate with each other in investigating the killing of at least 12 Chinese sailors on a section of Mekong River earlier this month, senior Chinese and Thai officials said in Chiang Rai on Sunday.

"We hope the Thai authorities will continue to give every possible convenience to the Chinese work team in Thailand and strive for progress in investigation," said Guo Shaochun, head of a team of officials dispatched by the Chinese government for works related to the attack.

The team is composed of officials from China's ministries of foreign affairs, public security and transport. They arrived in Chiang Rai Province in north Thailand on Saturday. Chinese officials and the Thai police conducted first joint investigation on the attacked ships Sunday morning in Chiang Rai's Chiang Saen district.

The Chinese people, leaders and media are greatly concerned over the investigation of the attack. The Chinese and Thai authorities are obliged to solve the case and bring the killers to justice, said Guo, who is also deputy head of the Department of Consular Affairs of China's Ministry of Foreign Affairs.

The Thai police will give full and proactive support to the work of the Chinese team and launch joint investigations to solve the case as soon as possible, said Pansiri Prapawat, Thailand's deputy police chief.

The Thai police have attached great importance to the case and the concerns of the Chinese side. The police have set up a team of experts and heads of various police departments to investigate the incident, Pansiri said.

At least 12 Chinese sailors on two cargo ships were killed in an attack by unidentified armed people on Oct. 5 on Mekong River. One Chinese sailor is still missing.