Tariq Abu Khder (center), a Palestinian-US teenager who was allegedly beaten during police custody, is hugged by his mother (left) following a hearing at Jerusalem Magistrates Court on Sunday. Photo: AFP

Israeli police made dozens of arrests overnight as violent protests over the murder of a Palestinian teenager by suspected Jewish extremists swept Arab Israeli towns into Sunday.

The military meanwhile carried out 10 air strikes on Gaza in response to persistent rocket fire into southern Israel as hopes faded of a renewed truce with its Islamist foe Hamas.

Violence which rocked annexed Arab east Jerusalem for four straight days after the kidnap and murder of the Palestinian teenager on Wednesday, spread to half a dozen Arab towns in Israel on Saturday.

The initial results of a post-mortem found that the 16-year-old was likely burned alive in what many Palestinians believe was a revenge killing by Jewish extremists after the kidnap and murder of three Israeli teenagers in the occupied West Bank last month.

"Around 35 people were arrested overnight, almost half of them minors," police spokeswoman Luba Samri told AFP.

Of those, 22 were arrested in and around the northern city of Nazareth, the most populous Arab town in Israel.

The rest were arrested in Taibe in the north and the Triangle region around Umm el Fahm, an Islamist stronghold northeast of Tel Aviv, where clashes continued into Sunday, Samri added.

"We are demonstrating against this incitement to hatred by Israelis online, who are saying 'death to Arabs,'" one demonstrator in the Triangle town of Qalansuwa told army radio.

Israeli police confirmed they had opened an internal investigation into allegations of police brutality following the publication of a video showing border police beating a handcuffed detainee.

The video was released as news emerged that a 15-year-old Palestinian with US citizenship had been badly beaten while in police custody in east Jerusalem, triggering condemnation from the US State Department.

A Jerusalem court ordered Sunday that the Palestinian American teenager, Tariq Abu Khder, be released to house arrest for nine days pending an investigation into stone-throwing allegations.

Tariq Abu Khder, who holds US citizenship and lives in Florida, is a cousin of Mohammed Abu Khder, a 16-year-old Palestinian whose kidnap and murder by suspected Jewish extremists on Wednesday sparked four straight days of riots.

Also on Sunday, the army said it had arrested a Palestinian in the flashpoint southern West Bank city of Hebron, whom the Israeli media suggested was somehow linked to the kidnap and murder of the three teenagers.