The leader of Egypt's Muslim Brotherhood has suffered a heart attack in jail, according to state-run newspaper al-Ahram.
The paper added that Mohamed Badie was in a stable condition. The al-Nahar website cited security forces as saying the 70-year-old had died, but that was denied by state-run news agency MENA.
Many of the Brotherhood's leaders were imprisoned in recent weeks, during a draconian crackdown which followed the military coup which deposed Mohamed Morsi. Badie was arrested after he was found in an apartment near where Morsi supporters held a six-week sit-in protest that was violently cleared by police.
According to Reuters, Brotherhood spokesman Gehad el-Haddad said he had no information on Badie's health. The agency also quoted a source saying his heart attack resulted from the "bad psychological state that he is going through".
Badie and his influential deputy Khairat el-Shater -who is also in custody - were due to face trial later this month for their alleged role in the killing of eight protesters outside the Brotherhood's Cairo headquarters in June.
The removal of Mr Morsi, Egypt's first democratically elected president, came after four days of mass protests in Cairo and elsewhere demanding he step down for abusing power. Shortly after came the massacre of several hundred Islamists by armed police in eastern Cairo.