The death of a Palestinian prisoner under Israeli interrogation after a week of demonstrations for the release of four other inmates on hunger strikes triggered fresh clashes Sunday and heightened concerns in Israel about a swelling wave of unrest in the West Bank.

The Palestinian Authority said that the results of an Israeli autopsy attended by the chief Palestinian forensic pathologist showed that the prisoner had been tortured. But Israel’s health ministry said the preliminary findings could not determine the cause of death, though they did not support initial Israeli assertions that the prisoner had died of cardiac arrest.