Tran Van Sy, deputy director of the Kien Giang general hospital, said the patients were transferred from the An Bien District medical center with signs of methanol poisoning.
Three of them were in critical condition and have been put on ECMO machines that pump and oxygenate a patient's blood outside the body.
Huynh Van Dan, chairman of the Nam Yen Commune People's Committee, said the poisoning happened at a four-day (November 2-5) funeral.
"There were over 150 people at the funeral who drank around 100 liters of alcohol," Dan said, adding that the alcohol was purchased from two locations in the commune. Alcohol samples have been taken for analysis and results are awaited.
The An Bien District medical center said that the person whose funeral was being held had also drunk at a party with friends and complained of chest pain and dizziness later. He had died on November 2. The center had said the cause of death might be alcohol poisoning, though authorities have yet to determine where the alcohol was purchased from. The friends who drank with the deceased have not shown signs of poisoning, the center said.
An investigation is ongoing.