A police statement said that protesters cut off the north-south highway 4 in the predominantly ultra-Orthodox city of Bnei Brak in an "illegal demonstration", the latest of several spurred by arrests of young ultra-Orthodox men accused of dodging military service.

An AFP journalist saw demonstrators sitting down or laying in the middle of a neighbouring street and mounted officers riding among them to disperse the crowd while a water cannon sprayed the protesters.

"Four police officers were injured lightly after stones were thrown at them," police said.

Israeli law requires men to serve two years and eight months in the military on reaching the age of 18, while women must serve for two.

Ultra-Orthodox men are excused from military service if they are engaged in religious study, but must still report to the army to receive their exemption.

Some seminary students have refused even to do that.

There have been protests in Bnei Brak and Jerusalem since the beginning of March, after the arrest of a young ultra-Orthodox man who failed to show up to request an exemption after receiving a call-up notice.