Khartoum - The family of a detained Sudanese youth activist, held for 50 days without charge, on Wednesday alleged he has been tortured in detention.
Tajalsir Jaafar, 28, is one of three activists whose condition a United Nations expert raised concerns about last week.
Jaafar is "in danger", his mother Sabah Osman Mohammed told AFP, unable to say more through her tears.
"He is suffering very much. His body is full of injuries," said Jaafar's younger brother, Ahmed Jaafar Tajalsir, 25.
"They beat him in his face."
A security source said that if the family has such a complaint they should take it to a prosecutor, rather than raising it in the media.
Rally for peace
From late 2011 to early 2012, Jaafar spent almost two months in custody without charge after helping to lead a University of Khartoum protest, he told AFP after his release.
He said he was beaten in custody, allegations which the National Intelligence and Security Service (NISS) denied at the time.
Jaafar said he had earlier been detained for short periods while campaigning for Girifna, a non-violent movement seeking an end to President Omar al-Bashir's government.
This time, he and the other two activists were detained outside the university on 12 May, Girifna said.
The campus had been in turmoil, with clashes between pro-government youths and their opponents, after a student was killed during a campus rally for peace in Darfur.
Ahmed Jaafar Tajalsir said the family had been able to visit Jaafar on Wednesday in the Khartoum-area Kober Prison, for only the second time since he was detained.
Jaafar is being held without charge, his brother said. Visits can only take place when security agents call and tell the family to come, he said.
Mashood Adebayo Baderin, the UN independent expert on human rights in the Sudan, last week told reporters he was concerned about the cases of Jaafar, Moamer Musa Mohammed, and Mohammed Salah.
Speaking to reporters at the end of his latest mission to Sudan, Baderin said he "had information from various sources" that Salah "was being tortured".
Baderin said the NISS refused his request to visit Salah to verify his condition.