The Chinese premier also says he expects even closer ties to develop between the six nations that share the Lancang-Mekong River. Our reporter Martin Lowe has more from the Cambodian capital Phnom Penh.
At more than four and a half thousand kilometres long, the Lancang-Mekong is the longest river in Southeast Asia - and the most controversial.
Governments build dams to harness its hydropower and produce electricity. They say dams control the water, preventing flood or drought. China opened a dam in 2016 when Vietnam was desperately short of water.
But environmentalists claim they can interfere with fish stocks on which millions downstream depend for food and reduce flow needed to irrigate the rice fields.
MARTIN LOWE PEACE PALACE, PHNOM PENH Managing these competing demands is a difficult job but it's one that this organization, the Lancang-Mekong Cooperation is tackling head on. Many say great progress has been made in only a short time.
Looking to develop growing co-operation between Lancang-Mekong nations is the Chinese premier Li Keqiang. He's leading discussions here in partnership with Cambodian prime minister Hun Sen. Government leaders from the remaining four nations are also attending.
SIPHAN PHAY CAMBODIAN GOVERNMENT SPOKESMAN "The Mekong-Lancang river is the river for peace, sustainability, growth and the economy."
The LMC is the only body that includes all six countries the Lancang-Mekong flows through: China, Myanmar, Thailand, Laos, Cambodia and Vietnam.
DR. SIRIPETCH TRISANAWADEE THAMMASAT UNIVERSITY, BANGKOK "My view is that we need to focus on developing the river with a sense of responsibility and sustainability, taking into account the needs of each country."
After little more than two years of operation, the LMC – created by China - has already brought Lancang-Mekong countries closer together.
Reaching consensus is a key aim – and a contentious move to dynamite rocks to clear a route for shipping has been put on hold, whilst more investigations take place. Martin Lowe, CGTN, Phnom Penh.