The South Sudanese government must end arbitrary detentions by the security agency before the return of opposition leader, Dr Riek Machar, the Amnesty International demands.
Dozens of men are being held in nasty conditions without charge or trial for months or years, says Amnesty International in a statement.
Amnesty International has compiled a list of 35 men arbitrarily detained by the National Security Service at its headquarters in Juba.
Some of the detainees have been held for close to two years without access to lawyers, says Amnesty International.
The detainees have very limited access to their families and the outside world, the rights body decries.
Sarah Jackson, Amnesty International’s Deputy Regional Director for East Africa names some of the detainees as former Western Equatoria State Governor, a 65-year-old Juba University Professor, a Ugandan aid worker and a journalist employed by UN-run Radio Miraya.
The detainees lack access to adequate food, medical care and sanitary facilities, the official says.