BEIJING - ELEVEN girls died of carbon monoxide poisoning at a school in northern China's Shaanxi province, an education official said on Tuesday evening. A news report said the girls had lit a fire to keep warm.

A dozen girls were found poisoned on Tuesday morning at the Duiziliang Middle School in Yulin city, said an official with the Yulin Education Bureau, who gave her family name as Fan.

She said 11 girls were confirmed dead, with another being treated at a hospital.

Ms Fan, reached by phone, said she had no further details. Telephone calls to Yulin's Public Security Bureau rang unanswered on Tuesday evening.

The Xinhua News Agency said the girls died Monday after lighting the fire to keep warm. The report said the 12th girl was in serious condition.

Xinhua did not say if the room was a classroom or a dormitory.

Carbon monoxide detectors are not required in schools in China, though the Education Ministry last year asked schools that can afford them to install detectors if they burn coal for heating.

The Xinhua report also did not give the ages of the girls or other details. It said the provincial vice governor had arrived to help investigate the case. -- AP