Saif Abu Keshek and Brazilian Thiago Ávila were held for a week in Ashkelon after Israel intercepted the 22-boat Global Sumud Flotilla near Crete.
Adalah said the detention was unlawful and involved psychological abuse, while Israel said it had investigated suspicions of terrorist links and illegal activity, allegations both men denied.
Brazil, Spain and the UN had called for their release, as the flotilla sought to challenge Israel's Gaza blockade amid continuing warnings over the territory's dire humanitarian conditions.
After activists' torture claims, what accountability exists for actions in offshore detention centers?
With €20 billion in trade, why is the EU divided on sanctioning Israel over human rights?
Can a naval blockade justify seizing a foreign ship in international waters under maritime law?