Four Chinese cargo ships and a Myanmar patrol boat were attacked early morning on Jan 4 at Wan Pung Port in Myanmar, further aggravating safety concerns over the Mekong River that saw a bloody slaughter of 13 Chinese sailors last October.

The People's Daily reported the Chinese ships included three cargo vessels - Baoshou 8, Baoshou 9 and Yuanfeng - and an oil tanker previously named Renda 3.

Sources from the naval police in Chiangsaen, Thailand said the attackers fired two rockets similar to the model M79. One fell into water while the other exploded near the ships. The Myanmar patrol vessel failed to mount an efficient counter attack due to poor visibility in the dark.

No casualties or damage to the vessels were reported.

13 Chinese sailors aboard two cargo ships were shot dead by a group of gunmen on Oct 5, 2011 in a section of the Mekong River that forms the border of Thailand, Laos and Myanmar.

The case is still undergoing trial. Thai police have said their country's servicemen were found to have been involved in the crime.

Shipping services on the river were suspended since then and then restored until December after Chinese police started joint patrols with counterparts from Thailand, Laos and Myanmar.

The Mekong River, known in China as the Lancang River, which flows through China, Myanmar, Laos, Thailand, Cambodia and Vietnam, plays a crucial economic role throughout the Greater Mekong Subregion (GMS).