Israeli settlers chopped down more than 100 olive trees belonging to Palestinians south of Nablus on Friday evening, a PA official said. The group tore down the produce in the valley neighboring the Tappuah settlement, between Yaduf and Jamain villages, Palestinian Authority official monitoring settlement activity Ghassan Doughlas said. Another group of settlers smashed two vehicles belonging to Palestinians in the same area on Friday night, Doughlas added. Cars belonging to Abdul-Rahman Muhammad Abdul-Rahman and Hasan Wasif Asayra, both from Asira al- Shamaliya, were vandalized on the main road between Huwwara village and Israeli settlement Yitzhar. Doughlas had on Monday urged Palestinians to take care on the Ramallah-Nablus highway, warning of revenge acts after Israeli forces took down four trailers at an illegal settlement outpost in the area. Extremist settlers have launched a campaign of "price tag" attacks, targeting Palestinians and their property in retaliation for perceived anti-settler actions by the Israeli government. Settler attacks in the West Bank against Palestinians increased by more than 50 percent in 2011, according to the UN Office for the Coordination of Humanitarian Affairs.