By Raneen Sawafta and James Mackenzie JENIN, West Bank/JERUSALEM (Reuters) -Israel sent tanks into the occupied West Bank for the first time in more than 20 years on Sunday as it ordered the military to prepare for an "extended stay" to fight Palestinian militant groups in the area's refugee camps.

A month-long sweep for Palestinian militants in the northern West Bank could continue for a year, Israel’s defense minister said, adding that residents who fled will be barred from returning and that a contested UN relief agency’s work there will be halted.