Vietnam's prime minister has urged health authorities to fight a hand, food and mouth disease outbreak caused by the EV71 virus which officials Wednesday said had killed at least 10 children this year.

The intestinal virus, which hits children hardest, has infected around 400 children this year, mainly in southern Vietnam, said Nguyen Huy Nga, head of the Health Ministry's Preventive Medicine Department.

"The virus killed at least 10 children in Vietnam in the first four months of this year," he told AFP, adding that no precise data was available because the enterovirus is not a notifiable disease in the communist country. Prime Minister Nguyen Tan Dung has urged health officials nationwide to take urgent measures to fight the disease, the state-run Vietnam News Agency said.

The virus, which begins with fever, blisters, mouth ulcers and rashes, is highly contagious and spreads through direct contact with the mucus, saliva or faeces of an infected person.

The virus has killed at least 28 children in neighouring China and infected thousands more, raising fears it could spread across the region.

"The virus is very contagious," Nga said. "There is a risk of infections from China through infected people moving between China and Vietnam."