The number of children infected with a deadly virus in eastern China has increased by nearly 700 in the last two days, state media reported Wednesday.

The virus, Enterovirus 71, has killed 20 children since it was discovered in March in Fuyan, a city in Anhui province.

No new fatal cases had occurred over the past five days, the official Xinhua News Agency reported. But it said the number of cases had increased to 1,884 from 1,199 in the last two days.

Numbers of infected children by Enterovirus 71 have steadily increased since hospitals in Fuyang began admitting patients with fever, blisters, ulcers in the mouth, or a rash on their hands and feet, according to the Anhui Health Bureau's Web site.

An official investigation into the cause of the outbreak has been launched, along with a prevention and control team to contain infected areas in the province, the bureau said.

The virus is most prevalent in the May to July months, but the health bureau said on its Web site that it cannot rule out the emergence of a new peak season for the virus as a result of the outbreak.

Several calls to the Anhui Health Bureau went unanswered Wednesday.

Enterovirus 71 is one of several viruses that cause hand, foot and mouth disease, which is characterized by fever, mouth sores and a rash with blisters. It is spread by direct contact with nose and throat discharges, saliva, fluid from blisters, or the stool of infected persons.

The illness mainly strikes children below age 10 and is not related to foot and mouth disease, which infects cattle, sheep and swine.

The World Health Organization's Beijing office said earlier this week that there did not appear to be an epidemiological link among the cases although most of the children lived in rural areas.