A detainee had his administrative detention renewed by in defiance of a military court ruling that he should be freed, a prisoners' advocacy group said.
The said 22-year-old Musllam Ghawanmeh's administrative detention was renewed on the same day he was due to be freed, official Palestinian news agency Wafa reported.
An Israeli military court had said the detention order against Ghawanmeh should not be renewed again.
Israel detained Ghawanmeh, of Jalazone refugee camp in the occupied West Bank, over two years ago.
He received a seven-month jail term, after which he has been imprisoned under successive administrative detention orders.
Palestinians are subject to Israeli military courts in the West Bank in a highly controversial legal system that virtually always sees defendants convicted.
Despite living in the same geographical areas - and doing so in breach of international law - Israeli settlers are tried in civil courts while Palestinians effectively live under military law.
Administrative detention orders typically last for terms of three to six months, which can be renewed indefinitely.
Their use has been criticised by rights groups.
"In violation of the restrictions placed by international law, Israel makes routine, extensive use of administrative detention," leading Israeli human rights organisation B'Tselem said in April.
said administrative detention "may be lawful in certain circumstances" in a February report that found Israel was engaged in a system of apartheid against Palestinians but added that they more often used to punish Palestinians.
"Israel's systematic use of it against Palestinians indicates that it is used to persecute Palestinians, rather than as an extraordinary and selective security measure," it said.