Israel faced mounting pressure Saturday over its detention of a Gaza hospital chief during a raid on one of the last functioning medical facilities in the battered north of the Palestinian enclave.

Israel has in recent days confirmed it is holding Dr. Hussam Abu Safiya and defended its assault that shut down Kamal Adwan Hospital, saying that the prominent pediatrician was suspected of “involvement in terrorist activities, and for holding a rank” in Hamas, which it said had made the site a…