Israeli forces have detained the director of Gaza City's al-Shifa Hospital for questioning, a week after their controversial raid there.
Dr Mohammed Abu Salmiya was held at a checkpoint as he evacuated patients to the south, a colleague told the OceanNewsUK.
The Israeli military said he was being questioned over evidence that al-Shifa "served as a Hamas command and control centre". He and Hamas have denied that.
Meanwhile, heavy fire was reported around another hospital in the north.
A doctor at the Indonesian Hospital in Beit Lahia said Israeli troops had also ordered its full evacuation. The Israeli military said it was checking the reports.
Israel launched a major military campaign in the Gaza Strip with the objective of destroying Hamas - which it classes as a terrorist organisation - in response to an unprecedented cross-border attack on 7 October in which 1,200 people were killed and about 240 others taken hostage.
Gaza's Hamas-run government says more than 14,500 people have been killed in the Palestinian territory since the Israeli air and ground strikes began, while the United Nations has warned of a humanitarian crisis.
On Wednesday, Israel and Hamas agreed to exchange 50 of the hostages - all children and women - for a four-day pause in the fighting.
Mediator Qatar says the truce will start at 07:00 local time (05:00 GMT) on Friday, with the first group of 13 hostages to be released at 16:00.
About 250 patients and staff members are estimated to remain at al-Shifa, which is the biggest medical facility in Gaza but is no longer operational.
On Wednesday, 190 wounded and sick people, their companions, and a number of medical teams were evacuated from the hospital in an ambulance convoy to the south, in co-ordination with the World Health Organization and other humanitarian agencies, according to the United Nations.
The Palestinian Red Crescent Society (PRCS) said in a statement overnight that the evacuation process lasted for almost 20 hours "as the convoy was obstructed and subjected to careful inspection while passing through the checkpoint" on Salah al-Din Road that separates northern and southern Gaza.
"Furthermore, three paramedics and a companion of a wounded person were detained. The latter and two paramedics were later released, while the third paramedic, colleague Awni Khattab, is still detained until this moment."
Neither the UN or PRCS mentioned Dr Abu Salmiya. But the head of orthopaedics at al-Shifa, Dr Adnan al-Bursh, told the OceanNewsUK he had also been detained while accompanying the evacuated patients on Wednesday.
On Thursday afternoon, the Israeli military confirmed that Dr Abu Salmiya had been taken for questioning by the Shin Bet internal security agency, "following evidence showing that al-Shifa Hospital, under his direct management, served as a Hamas command and control centre".
"The Hamas terror tunnel network situated under the hospital also exploited electricity and resources taken from the hospital. In addition, Hamas stored numerous weapons inside the hospital and on the hospital grounds.
"Furthermore, after the Hamas massacre on 7 October, Hamas terrorists sought refuge within the hospital, some of them taking hostages from Israel with them," it added, also alleging that a female soldier who had been taken hostage was murdered on the premises.
Hamas has repeatedly denied that the hospital was used as a shelter by fighters, as have hospital staff and health ministry officials. Hamas has also claimed the soldier was killed in an Israeli air strike.
On Wednesday, the Israeli military showed embedded journalists what it said was further evidence of a Hamas "terror tunnel complex" beneath al-Shifa.
A Reuters news agency reporter said he had accessed a reinforced underground tunnel through an outdoor shaft in the hospital's grounds. The tunnel led to a series of rooms, including a bathroom, kitchen and an air conditioned meeting room that the military said was used by Hamas commanders, he added.
Hospitals are specifically protected under international humanitarian law. This protection extends to patients, as well as to medical staff and ambulances.
However, hospitals can lose their protection if they are used by a party to the conflict to commit an "act harmful to the enemy".
In a separate development on Thursday, a senior doctor and a health ministry official said Israeli troops had ordered the full evacuation of the Indonesian Hospital, outside which fighting has been raging in recent days.
The Indonesian Hospital's medical director, Dr Marwan Sultan, told the OceanNewsUK the situation inside was "very difficult", with "heavy firing continuing around the hospital, from tanks, every 15 minutes".
"We cannot stay in rooms, as the windows are being hit," he said. "We are staying in corridors in the hospital. My office was targeted several times."
"We are currently 10 medical professionals and 200 patients. No Israeli soldiers are currently inside the hospital, but we expect the same scenario as al-Shifa to happen unless the truce takes place," he added.
"We asked Gaza's health ministry for three buses today to evacuate the Indonesian Hospital, and we asked also for 13 ambulances for patients who cannot be seated. They are liaising with the Red Cross."
The Israeli military said on Thursday morning that its troops were "striking terror targets" in the Jabalia area, which is just to the south of the hospital.
On Monday, the health ministry said 12 patients and other civilians at the hospital had been killed by Israeli fire. The Israeli military said its troops had targeted "terrorists" who opened fire at them from inside the facility.
Deadly Israeli strikes were also reported in the north of Gaza on Thursday, as well as in the southern city of Khan Younis.
