The rights group, Amnesty International says a lecturer at the University of Juba, Prof Leonzio Angole Onek has been in detention for the last three months and should now be released or charged.

It says Professor Angole was arrested on December 7 while driving from the Juba campus to his home near to the compound.

Amnesty International says two vehicles blocked his car on the road and three officers pulled him out of his car. They handcuffed him and drove away with him.

The group says Professor Angole was not charged or given any reason for the arrest. And since then, he has not been given access to his family and lawyer, but was periodically allowed to seek medical car in Juba.

It says Professor Angole taught at the University of Juba since 2010 and was appointed Dean of the College of Applied and Industrial Sciences in 2014.

In a statement, the group says the lecturer should be charge of an offence consistent with international standards or released immediately.

Amnesty International also urges authorities to ensure that the lecture is not to subjected to torture and that he is allowed access to lawyers and family members.