Seven Laotian villagers entered the cave in central Xaysomboun Province, about 125 kilometers (78 miles) north-east of the capital Vientiane, on May 20, state-run Laophattana News said.
They were searching for gold but were trapped inside the cave after heavy rain triggered flash flooding, blocking their exit, it added.
Authorities and villagers have been working to pump water out of the cave, but rescue teams have not been able to reach the group.
"We still do not know whether there are any signs of life or if they are still alive," Bounkham Luanglat, president of a Laotian volunteer rescue association, told AFP.
About 100 people from Laos and Thailand have gone to the site in Long Chanh District to help in the rescue operations, the association said.
