Doctors were investigating whether dozens of girls were poisoned at a high school in northern Afghanistan yesterday, after 61 girls went to hospital complaining of a sudden illness, officials said.

Dr Khalil Farangi said the 61 students and one teacher from Hora Jalaly high school in Parwan province northwest of Kabul complained of symptoms such as irritability, weeping and confusion. Several girls also passed out.

The mass hospitalization comes about two weeks after a similar incident in Parwan, where dozens of girls were hospitalized in late April after being sickened by what Afghan officials said were strong fumes or a possible poison gas cloud.

The Taliban and other conservative extremist groups in Afghanistan oppose education for girls, who were not allowed to attend school under the 1996-2001 Taliban regime. Though it was unclear if yesterday's incident was the result of an attack, militants have previously attacked schoolgirls in the south by spraying acid in their faces and burned down schools as a protest against the government. Scores of Afghan schools have been forced to close because of violence.

Officials yesterday sent blood samples to Kabul and to the main United States base in Bagram to test whether some form of poison was to blame, said Farangi, the director of the local hospital.

Provincial Governor Abdul Basir Salangi said an investigation is under way.

A number of students interviewed at the hospital by reporters complained of a strong sweet smell, which gave the students headaches and made some girls dizzy before they passed out.

"There was a very strong smell, like flowers in the hallway. I fell down and woke up in the hospital," said 18-year-old Zahera, who, like many Afghans, goes by one name. She lay in a ward full of girls, many of them two to a bed, wearing the typical Afghan school uniform of a black robe and white headscarf.

Sadia Akbari, who was shaking and sweating in a hospital bed, said she smelled something while sitting in religion class and asked a friend if it was her perfume.

"But then we went outside to the yard and the perfume smell was stronger out there," 18-year-old Akbari said.

Akbari said she left the school with rest of the girls and went home, but she kept feeling dizzy and her eyes were stinging.

Several hours after the incident, about three dozen students remained in hospital. They were receiving glucose intravenously and oxygen. 61 Afghan girls suffer possible gas attack.