The rights group reports Sudanese national security forces arbitrarily arrested more than two dozen people in Khartoum following rebel attacks in southern Sudanese states. Most have been released since their April arrests, though seven are allegedly held incommunicado in secret locations.
Daniel Bekele, Africa research director at Human Rights Watch, said 12 students from Darfur were arrested on similar charges in June and authorities in May banned demonstrations planned by student groups aligned with a rebel movement.
"These arrests fit a pattern of retaliation against civilians from areas where rebels are fighting government forces," he said in a statement from Nairobi.
Bekele said the government sanctioned arrests suggest national security laws in Sudan are "draconian"
Peace negotiations between the Sudanese and South Sudanese have faltered over rebel claims by both sides.
South Sudan marked its second anniversary as an independent nation Tuesday. Independence was secured as part of a 2005 peace deal ending a civil war which claimed 2 million Sudanese lives.
Rebel conflict, border disputes and issues related to oil revenue have threatened the fragile peace.