The attack was blamed on hardliners angered by plans to curb settlements
Israeli PM Benjamin Netanyahu has condemned an attack on a mosque in the occupied West Bank and called for the arrest of those responsible.
Jewish settlers are suspected of launching the attack, burning books and scrawling hate-messages in Hebrew.
The main prayer hall and library of the mosque in the village of Yasuf were badly burnt in the attack on Thursday.
Clashes later broke out between villagers and Israeli troops sent to investigate the incident.
In a statement, Mr Netanyahu "vigorously denounced the aggression against the mosque".
He said he had told security forces "to act with determination to find the perpetrators and bring them to justice".
Other Israeli leaders added their voices to the condemnation.
On Saturday, Israeli President Shimon Peres called it "an incendiary criminal act against all the moral principles of the state of Israel".
"The government, security forces and all authorities must spare no effort to catch the guilty parties," he said.
On Friday, Defence Minister Ehud Barak branded the attack "an extreme act meant to harm the government's attempts to advance the process for Israel's future."
Jewish settler groups have recently reacted angrily to Mr Netanyahu's decision to scale back settlement building in the West Bank.
Palestinian officials have refused to rejoin peace talks until a total freeze is imposed.
All Jewish settlements in the West Bank, including East Jerusalem, are considered illegal under international law, though Israel disputes this.