German health authorities say the number of children that have fallen ill with vomiting and diarrhea after eating food from school cafeterias and daycare centres has risen from about 4,500 to 8,400.

Authorities in Berlin and the surrounding eastern German states reported the new gastroenteritis cases Saturday, while laboratory investigations to determine the exact cause of the outbreak were still under way.

Berlin's health department says the sicknesses are moderate and most children recover within two days without requiring to be hospitalized.

In Saxony state, at least 16 cases of norovirus, a mostly food- or water-borne illness, were proven, according to German news agency dapd.

The government-affiliated Robert Koch Institute said Friday that all facilities where the illness occurred likely received food from a single supplier.