Hundreds of girls at a Mexican boarding school run by Roman Catholic nuns have been hit by a mystery illness that the authorities say is psychological.
Parents take their children from the school - many unable to stand
Headmistress Margie Cheong, a nun from South Korea, said it was unclear what causes the symptoms, which include difficulty walking and nausea.
Some 600 of the 4,000 pupils at the Villa de las Ninas school outside Mexico City have been affected.
The outbreak has prompted allegations of abuse by the nuns.
Mother Superior Margie Cheong said she regretted not immediately informing parents, when the first cases occurred in October.
"I couldn't advise them," she said. "This was too big, and I couldn't tell them what the girls had because there was no diagnosis."
Headmistress Margie Cheong denies she mistreated her pupils
Once the school told students in March about the findings, 80% recovered. About 130 pupils are still experiencing symptoms, she said.
The girls are only allowed to see their families three times a year. Some of the students have complained of strict punishments like being made to sleep in an animal enclosure.
Some also complained about the nuns treating them with traditional Asian medicine.
Government psychologists will interview pupils on Monday to find out what happened at the school, which offers a free secondary education to children from poor families.
Margie Cheong denied she had mistreated her pupils but said she would accept responsibility if the government investigations said otherwise.
Villa de las Ninas is run by the Sisters of Mary, a religious order founded in South Korea by US-born Aloysius Schwartz, who died in 1992.