Two children, aged four, were taken to Sofia's Pirogov emergency hospital on January 28 with symptoms of poisoning, just two months after 18 children from the same kindergarten had to be hospitalised with similar symptoms, Focus news agency reported on February 1.

In the incident in November, the children had accidentally eaten pills containing strong sedatives, mistaking them for candy, which they found in the purses of two of the kindergarten's employees.

Most of the children had to spend several days in hospital then, and the two children admitted to Pirogov earlier this week were also among those affected in November.

One of the two employees blamed for the November incident was also on duty on January 28, Focus news agency reported.

The case is investigated by Sofia's city hall, deputy mayor for education Yordanka Fandukova said, as quoted by Focus news agency, but she refused to link the two incidents.