The alleged attackers were seen heading in the direction of the nearby Elon Moreh settlement after setting fire to the trees on land owned by the Palestinian village of Salem, village council spokesman Adli Ishtayeh said.

He said that the trees were on ground adjoining the settlement and, for reasons of Israeli security, kept off limits to their owners for most of the time. He said that the Israeli army, which polices the area, had been notified.

A military spokesman said no complaint against the settlers had been made and that troops on the scene were treating the incident as a fire, not arson after unseasonably hot and dry weather.

Since the start of the olive harvest last month, there have been scores of Palestinian complaints about settlers cutting down trees, stealing olives or preventing farmers from harvesting their crops, rights groups and police say.

A senior Israeli intelligence officer acknowledged that there had been acts of violence and vandalism by Jews in the West Bank, noting in particular recent attacks against mosques there.

We are not happy about the situation connected with Jewish extremists in the West Bank, he told a group of foreign journalists on Sunday, speaking on condition of anonymity.