More than 100 girls at a school in northeastern Afghanistan were admitted to the hospital Tuesday after getting sick from drinking water believed to be poisoned by an opponent of education for girls, an official told Agence France Presse.

"I think some radical elements who oppose girls going to school are behind this act," district governor Mohammad Hussain told AFP, adding that police were looking into the incident.

The schoolgirls suffered symptoms of poisoning such as nausea and headaches after drinking water from a tank at the high school in Takhar, according to AFP.

Haffizullah Safi, head of Takhar's public health department, said: "This is not a natural illness. It's an intentional act to poison schoolgirls," according to Reuters.

Abdul Saboor, spokesman for the education ministry, said he believed it may have been a smaller incident and that an investigation had begun.

"According to our reports, a number of these schoolgirls were panicked and taken to hospital and they were then quickly dismissed,” he told AFP.

One official told Reuters that some of the approximately 150 girls were in critical condition.

Before a U.S.-led invasion in 2001, the Taliban had banned Afghan girls from attending school or working in offices.