Mohamed al-Faki Suleiman was picked up near his home in the capital Khartoum, relatives say.

This follows the arrest of two other politicians last week.

They were part of a task force trying to dismantle the network established by the former president Omar al-Bashir.

It was also attempting to recover money and assets looted during his three-decade rule.

Sudan is in the midst of a political and economic crisis following a coup in October which derailed a timetable towards elections.

Since the coup there have been massive demonstrations against the military.

Security forces have killed about 80 protesters.