Jerusalem (AFP) - Suspected Jewish extremists set fire to a Greek Orthodox seminary building in Jerusalem early Thursday, police said, 24 hours after a mosque was torched in the West Bank.

The vandals torched an annexe of the seminary near the walls of the Old City and scrawled "graffiti insulting Jesus", police spokeswoman Luba Samri said, describing it as a "nationalist" attack.

Police said the assailants set fire to the toilet and shower block at the seminary, causing damage but no injuries.

Israeli President Reuven Rivlin condemned the attack.

"It is inconceivable that an act like this could happen in a house of prayer. This is a heinous crime, there must be an investigation and those responsible must be brought to justice," his office quoted him as saying in a phone call to Greek Orthodox Patriarch Theophilos III.

"Such criminals not only threaten to set fire to places of worship holy to all of us, but ignite the regional powder keg upon which we all sit," he added.

Israel's foreign ministry said it expected the police to bring the perpetrators to justice.

"We condemn any action of religious intolerance of any kind," it said in a statement.

"The government of Israel is committed to protecting the rights and freedoms of all its citizens, regardless of race, creed, or beliefs."