Nazareth - As tens of thousands of Christian pilgrims converge on the Holy Land this week to celebrate the birth of Jesus, senior Israeli rabbis have announced a war on the Christmas tree.In Jerusalem, the rabbinate has issued a letter warning dozens of hotels in the city that it is "forbidden" by Jewish religious law to erect a tree or stage new year's parties.Kosher statusMany hotel owners have taken the warning to heart, fearful that the rabbis may carry out previous threats to damage their businesses by denying them certificates declaring their premises to be "kosher".In the coastal city of Haifa, in northern Israel, the rabbi of Israel's premier technology university has taken a similarly strict line. Elad Dokow, the Technion's rabbi, ordered that Jewish students boycott their students' union after it installed for the first time a modest Christmas tree.He called the tree "idolatry", warning that it was a "pagan" symbol that violated the kosher status of the building, including its food hall.About a fifth of the Technion's students belong to Israel's large Palestinian minority.While most of Israel's Palestinian citizens are Muslim, there are about 130 000 Christians, most of them living in Galilee. More Palestinian Christians live under occupation in East Jerusalem, which Israel has annexed in violation of international law."This is not about freedom of worship," Dokow told the Technion's students. "This is the world's only Jewish state. And it has a role to be a 'light unto the nations' and not to uncritically embrace every idea."For most of Israel's history, the festive fir tree was rarely seen outside a handful of communities in Israel with significant Christian populations. But in recent years, the appeal of Christmas celebrations has spread among secular Israeli Jews.Buy Santa hatInterest took off two decades ago after one million Russian-speaking Jews immigrated following the fall of the Soviet Union, said David Bogomolny, a spokesperson for Hiddush, which lobbies for religious freedom in Israel.Many had little connection to Jewish religious practice in their countries of origin and had adopted local customs instead."The tree [in the former Soviet Union] was very popular but it had nothing to do with Christmas," he said. "Each home had one as a way to welcome in the new year."Nazareth, which claims to host the tallest Christmas tree in the Middle East, has recently become a magnet for many domestic tourists, including Jews, Christians and Muslims. They come to visit the Christmas market, hear carols and buy a Santa hat.