KUNMING, Nov. 21 -- The 28th round of joint patrols on the Mekong River in the Golden Triangle region concluded Friday afternoon.

The four-day patrol -- launched by China, Laos, Myanmar and Thailand -- saw 19 ships, 47 personnel and 890 tonnes of cargo scrutinized by police, according to the border defense force in southwest China's Yunnan Province.

The joint force also spoke with sailors and locals, and distributed police contact cards and pamphlets on narcotics.

The four countries also exchanged information on security along the river, vowing to deepen cooperation to address criminal activities, such as gun and drug smuggling.

Commander of the patrol fleet, Jin Shangwen, said the task faced by the fleet was grim, citing, as an example, Thailand, which this month had seized more narcotics than last month.

He said the four countries would continue to strengthen cooperation to crack down on cross-border drug crime.

The joint patrols started in December 2011 after a gang hijacked two cargo ships on Oct. 5, 2011 in Thai waters and killed 13 Chinese sailors.