Sudanese protesters rallied after Friday prayers in an eastern town against the death in custody of a teacher arrested in connection with anti-government demonstrations sweeping the country, witnesses said.
An investigator on Thursday confirmed that teacher Ahmed al-Kheir, 36, had died from wounds sustained while in detention after he was arrested last week by security agents in the eastern town of Khashm el-Girba.
Kheir, a member of Sudan's Islamist Popular Congress Party, was detained for allegedly organising anti-government protests, a relative told AFP.
On Friday, crowds of protesters in Khashm el-Griba staged a rally after the weekly Muslim prayers to protest his death.
"We will give our blood to keep you alive," chanted the protesters, who emerged from several mosques after prayers and held a march, a witness told AFP by telephone.
Kheir was arrested by agents of the country's powerful National Intelligence and Security Service (NISS), his uncle Ahmed Abdelwahad told AFP as the family took his body from a mortuary.
"We have asked the chief of NISS in Kassala to bring the security agents who interrogated Kheir in Khashm el-Girba," Amer Ibrahim, the head of an investigative committee at the prosecutor's office, told reporters on Thursday, indicating he had died in detention.
"The man had wounds on the back, legs and other parts of his body that led to his death," Ibrahim said.
Deadly protests have rocked Sudan since December 19, with demonstrators holding nationwide rallies calling on President Omar al-Bashir to resign.
Officials say 30 people have died in the violence, while rights group Human Rights Watch says at least 51 people have been killed.
Demonstrators on Friday also staged rallies in a district of Khartoum and in Omdurman, the twin city of the capital, witnesses said.
Police fired tear gas as protesters rallied chanting "freedom, freedom" outside a mosque in Omdurman run by the main opposition Umma party, witnesses said.
Police dispersed the protesters and some tear gas canisters hit the compound of the mosque, a witness said.
Police and security officials were not immediately available for comment.
Umma's head, former premier Sadiq al-Mahdi, has thrown his weight behind the protests and called on Bashir to step down.
Bashir, who has refused to resign, swept to power in a 1989 Islamist-backed coup that ousted Mahdi's elected government.
Protests first erupted after a government decision to triple the price of bread but soon escalated into rallies against Bashir's three-decade-old rule.