In a landmark case, an Egyptian court ruled on Saturday that the state must recognise the right of Christians who convert to Islam to change their minds and revert to Christianity, court sources said.

Until now, Egyptian courts have upheld a traditional reading of Islamic law in such cases, prohibiting the conversion from Islam to any other faith, regardless of the convert's original religion.

While Egyptian law is largely secular and modelled on the French legal system, personal status issues such as conversion, marriage and divorce are governed by the religious laws of the relevant community. Egypt is primarily Muslim, but has a substantial Coptic Christian community as well.

Saturday's ruling by the Supreme Administrative Court said 12 people who had converted to Islam from Christianity and then back again could have their reversion to their original faith stated on their government identity papers.

Authorities had allowed the 12 to change their religious status on their identity documents when they converted to Islam, but had so far refused to allow them to change it back.

"This opens the door of hope to hundreds of Copts who converted ... and were then unable to return," said Mamdouh Nakhla, a human rights lawyer.

Nakhla said there were around 450 similar cases currently in litigation, and that estimates of the number of people who wished to revert to Christianity from Islam ranged to up to several thousand.

The court ruling, which cannot be appealed, overturned a lower court decision in April which said the state had no obligation to recognise a convert to Islam's decision to revert back to his original faith because it violated Islam's ban on apostasy.

The higher court's decision now obliges Egypt's ministry of interior to issue the plaintiffs with birth certificates and identity papers identifying them as Christians.

But the paperwork will note their previous conversion to Islam - a caveat one human rights activist said was an invitation to discrimination.

"This may solve some procedural issues, but ... will open the door to discrimination against those citizens by extremist officers or civil servants when they see in the entry that they left Islam," said Gamal Eid, head of the Arabic Network for Human Rights.

The Koran does not explicitly prescribe a penalty for apostasy, but considers it one of the gravest sins. However, traditions of the Prophet Mohammed and some of his companions call for the death penalty in some cases of apostasy.

Saturday's ruling comes less than two weeks after a court for the first time granted members of Egypt's tiny Baha'i community the right to obtain government identity papers - largely denied them for several years - as long as they omit their faith, since it is not officially recognised in Egypt.

But the same court that ruled in favour of the Baha'is also dismissed a case by a man who sought to have his name and religion changed on his identity papers to reflect his conversion from Islam to Christianity.

It said the ministry of interior had issued no administrative decision rejecting Mohamed Hegazy's request but noted it was "not correct" for a Muslim to convert.