Sudanese security services on Thursday arrested prominent government critic Mariam al-Mahdi, daughter of the premier whom President Omar al-Bashir ousted in a 1989 coup, as a crackdown on the opposition gathered pace.
Mahdi was arrested in Khartoum as she went with a group of activists to petition the security forces for the release of protesters detained nearly two weeks ago, a member of her Umma party said.
"The minute we stepped out of the car they arrested her," said Habab Mubarak, the daughter of another leading Umma party figure, Mubarak al-Fadil.
"They also violently grabbed the placards that we had in the back of the car showing pictures of those people who were detained on January 30," Mubarak said.
She said the incident took place after around 30 women, among them the mothers of those still in custody after anti-government demonstrations last month, set off to present their petition to the head of the Sudan's National Intelligence and Security Services Mohammed Atta.
They had gathered at the home of Fadil and were just leaving when the security forces arrested Mariam al-Mahdi, daughter of Sadeq al-Mahdi, the premier Bashir overthrew.
"There was a huge number of riot police trucks and security officials outside the house. They were everywhere," Fadil's daughter said.
The heavy security contingent followed them to the NISS headquarters, where her mother and two other women attempted to hand over their petition, while the rest of the women sat outside the building.
Mubarak said her aunt and two cousins were taken by the police, driven to separate locations far from the city centre and dropped at the side of the road.
The latest arrest comes amid a wider crackdown on opposition activity in the face of the mass protests rocking the regime in neighbouring Egypt.
A spate of localised but vocal anti-government protests broke out in Khartoum and other northern cities in north Sudan at the end of January, organised by student activists via the Internet.
The demonstrators demanded a change of regime, civil liberties and an end to debilitating price rises.
Police used tear gas and batons to disperse them and arrested more than 100.
Also in January, security police arrested Islamist opposition leader Hassan al-Turabi shortly after he said in an AFP interview that a popular revolt like the one that ousted veteran Tunisian strongman Zine El Abidine Ben Ali, was likely in north Sudan as the south voted for independence.
Last week, Human Rights Watch said the arrest of 16 people outside the communist party headquarters on Februay 2 was part of a pattern of repression.
"This fits in with the restrictions on the freedom of expression in Sudan, and the continued use of the national security apparatus, which has a long history of ill-treatment and torture, to detain journalists and activists," HRW's head of research on Sudan, Jehanne Henry, said.