Gaza's Islamic Hamas rulers ordered private medical clinics to shut down on Monday, in a challenge to Palestinian President Mahmoud Abbas that threatened to deepen hardship in the long-suffering territory. Earlier this month, hospital doctors across the Gaza Strip launched a work slowdown to protest the arrest of a prominent physician allied with Abbas' Fatah movement. On orders from Abbas' West Bank government, which pays their salaries, most curtailed their daytime hospital schedule to three hours a day, receiving patients afterward in expensive private clinics. Hamas struck back Monday by ordering the immediate shutdown of the clinics. Doctors who do not comply will be fired, and clinics will also be scrutinized to ensure they are properly registered and licensed, Hamas officials said. "We are not going to play with the health sector," said Khaled Radi, a spokesman for the Hamas health minister Abbas deposed after the Islamic militant group violently seized control of Gaza in June. There was no immediate comment from Abbas' government.