At least 25 girl students of Pabna Collectorate School and College in the town yesterday fell sick in their classroom due to 'mysterious reasons.'

Dr Shafiqul Hassan, medicine consultant at Pabna Medical College Hospital, said such illness is usually seen among girls. It is known as mass psychogenic illness (MPI) or mass hysteria.

Of the victims, 18, all aged between 13 and 14, were admitted to Pabna Medical College Hospital, while the rest were treated locally.

Mahmudul Hasan, a teacher of the school quoted the victims as saying that the students of class IX felt a bad headache and had respiratory problems after a bottle of liquid substance broke with a high sound beside their classroom.

Ajmal Hossain, additional deputy commissioner, said a three-member committee has been formed to probe the matter.

The committee was asked to submit its report within three working days, he added.