Palestinians said they felt "no joy" this Christmas as Israel bombed Gaza on Monday, with no end in sight to the war that Hamas says has claimed more than 20,000 lives.

Festivities were effectively scrapped in the occupied West Bank city of Bethlehem, revered as the birthplace of Jesus Christ, with few worshippers or tourists on the usually packed streets.

In the besieged Gaza Strip, the Hamas-run ministry of health said early Monday Israeli strikes had killed at least 18 people in the southern city of Khan Yunis, the center of recent fighting.