The number of children infected with a lethal intestinal virus that started in March in east China's Anhui Province has increased by nearly 700 in the past two days. The outbreak has befallen nearly 1,900 children and had killed 20 by Tuesday, health authorities said Wednesday.

According to a warning by the Anhui Health Bureau's website, the peak outbreak is expected to come in June and July. Though the outbreak began in early March, it was only reported this week.

The infection begins with fever, ulcers in the mouth, or a rash on the hands and feet, according to the Anhui Health Bureau's website. The illness - known as EV71 - mainly affects children under the age of 10.

Authorities are investigating the cause of the outbreak and launched a prevention and control team to contain infected areas in the province. The Ministry of Health has requested regions with EV71 outbreaks to report daily developments, Xinhua news agency reported.

The World Health Organization has also expressed concern about the number of deaths in the current outbreak, although EV71 has been reported in China before.