A mosque near the Palestinian West Bank city of Nablus has been damaged by fire, officials say.
Palestinian president Mahmoud Abbas says the fire was caused by Jewish settlers, and that it could jeopardise Israeli-Palestinian peace talks.
Israeli media reports reports said an electrical short circuit may have started the blaze.
But Israeli security officers investigating the fire have not yet determined its cause, police say.
The mosque was gutted by the fire, which also destroyed holy books.
Lubban al-Sharqiya, the village where the mosque lies, is close to three Jewish settlements, AFP reports.
The attack comes as US Middle East envoy George Mitchell has returned to the region, attempting to restart Israeli-Palestinian peace talks.
"This criminal attack threatens efforts to revive the peace process," said Mr Abbas in a statement.
He pointed the finger of blame at Israel, adding that "the Israeli army protects the settlers".
Israeli Trade Minister Binyamin Ben-Eliezer said the fire was probably caused by arson.
"I have no shadow of doubt their aim was to ignite fire in the region and this is lamentable," he was quoted as saying by Israel's army radio.
Hamas, which is opposed to peace talks with Israel, said the mosque attack is "the first fruit of the pointless negotiations," Reuters reports.
Israel warned Palestinians in the West Bank that there was a risk of local settlers attacking homes in the area after the Israeli army demolished houses in a settlement near Nablus, Palestinian officials say.
"We had an official warning yesterday that settlers may try to attack Palestinian homes because of the demolition of houses built without a permit", Nablus governor Jibril al-Bakri was quoted as saying by AFP.
The West Bank has seen a series of attacks on mosques in recent months.
Last month, another mosque in the village of Huwara near Nablus was vandalised by Hebrew graffiti. Palestinian residents blamed activists from three nearby Jewish settlements.
In January, Israeli police arrested settlers as part of investigations into an arson attack on a West Bank mosque in 2009.