An 11-year-old Christian girl has been detained in Pakistan for allegedly burning pages of the Koran and could face the death penalty if the charges are proved.

The girl is said be mentally disabled and suffering from Down's syndrome.

She was held by police after she was seen in public holding burnt pages which had verses from the Koran. A protesting mob demanded that the girl be arrested else threatened to burn down houses belonging to Christians.

Muslims in Mehrabadi contest that the girl was mentally challenged and say she was normal.

While many Christians from the outskirts of Islamabad have fled fearing reprisals, the girl's family has been given special protection. As the girl was suffering from mental disorder, officials believe she could not have desecrated the Koran.

"I don't think anyone will dare go back after this. The area is not safe for us now," a Christian in the region Arif Masih told the Guardian. The Christian community has been told to vacate the region before 1 September.

Pakistani President Asif Ali Zardari has called on officials to investigate.

"From the reports I have seen, she was found carrying a waste bag which also had pages of the Koran in it. This infuriated local people and a large crowd gathered to demand action against her.

"The police were initially reluctant to arrest her, but they came under a lot of pressure from a very large crowd, who were threatening to burn down Christian homes," Pakistan's minister for national harmony, Paul Bhatti, told the BBC.

The girl is expected to face court by the end of this month.

The incident has ignited a debate on religious tolerance in the country and the strict laws against blasphemy. Under the present law, a person can face the maximum death penalty for desecrating the Koran.

In recent times, those advocating review of the blasphemy law have come to grief. Shahbaz Bhatti, the minister for minority affairs, and Punjab governor Salman Taseer were assassinated within a period of two months after calling for a change in the law.