Thousands of ultra-Orthodox Jews have rallied in Jerusalem and other Israeli cities against the military draft and measures to force ultra-Orthodox Jews to serve in the Israel Defence Forces (IDF).
Police said 35 people were arrested.
A group of ultra-Orthodox militants based in Jerusalem called for the protests on Thursday.
The group rejects any compromise on the question of military service, The Jerusalem Post reported.
Two police officers were injured by thrown stones.
Several major streets were temporarily blocked by demonstrators, and in Ashdod a police car was set ablaze.
The protests were touched off by a court ruling to halt scholarship money for religious students who until now had been exempt from military service.
The High Court of Justice ruled on Tuesday to cut funding to students born in 1994, 1995 and 1996 who are enrolled at Orthodox Jewish schools.
Before the ruling their military service had been deferred.
Protesters voiced opposition to the detention of a student who did not attend a meeting at the IDF recruitment centre after he received a draft notice.
The unrest is part of a long-running fight over division of military service in Israel.
The High Court of Justice ruled two years ago that the practice of exempting ultra-Orthodox students from military service violated Israel's basic law and ordered new legislation be written.
