Clashes sparked by the murder of a Palestinian teenager have spread from east Jerusalem to Arab towns inside Israel, with autopsy reports showing he was burned alive.
Rocket fire targeting Israel from Gaza also increased on Saturday, raising fears of an escalation with the Islamist Hamas movement which controls the Palestinian enclave.
Mohammed Abu Khder, 16, was abducted from his Shuafat neighbourhood in occupied east Jerusalem early on Wednesday. His charred body was found hours later in a west Jerusalem forest.
Palestinians said Jewish extremists killed him in revenge for the kidnapping and murder in the West Bank last month of three Israeli teenagers.
Clashes following his death and funeral spread on Saturday to Arab towns in central and northern Israel, where roads were closed and dozens of demonstrators arrested.
Palestinian news agency Maan quoted attorney-general Mohammed Aluweiwi saying the initial findings of a post-mortem indicated the presence of smoke in the boy's lungs, suggesting he was alive while being burned.
Abu Khder also suffered a head wound but it was not the cause of death, Aluweiwi said.
Israeli police said they still could not confirm the motive for Abu Khder's murder.
A spokeswoman said police were investigating "all possibilities" and that there was a gag order on all details of the investigation.
The teenager's funeral on Friday, attended by thousands of mourners, led to a third straight day of clashes across Israeli-annexed Arab east Jerusalem.
Police reported disturbances in the Arab towns of Taibe in northeast Israel and Jaljulia and Qalansuwa in the centre on Saturday, also spreading to Umm el-Fahm, Arara and Nazareth.
But despite the violence, Israel did not consider it the beginning of a popular Arab-Palestinian uprising.
"I don't see a third intifada here," Internal Security Minister Yitzhak Aharonovitch told Channel 2 television during a tour of the north.
The road between Taibe and Tira stayed closed on Saturday, while a route near Qalansuwa was shut for several hours.
Police said one officer was injured by a stone near Arara, and around 35 Arab Israeli suspects had been arrested in clashes since Friday night.
Another 25 Palestinians were arrested in east Jerusalem and nearby West Bank clashes.
One of those arrested in east Jerusalem was Tariq Abu Khder, a 15-year-old cousin of the murdered Palestinian youth and an American citizen currently on holiday.
Police spokeswoman Luba Samri said police found a sling on Tariq, who had attacked police and resisted arrest, while others were throwing stones and Molotov cocktails, wounding six officers.