The head of the Gaza Strip’s biggest hospital has accused Israel of torturing him and other detainees, following his release after seven months in Israeli prisons and detention facilities. Mohammed Abu Salmiya, the director of al-Shifa hospital in Gaza City, was among dozens of Palestinians freed and returned to Gaza on Monday, according to Israeli authorities. The doctor, who had been held by Israel without charge since arrest at his workplace in November, said he and other prisoners were subjected to “almost daily torture” while in detention in Israel. Mistreatment included assaults with batons and dogs, deprivation of food and medicine, as well as physical and psychological humiliation, Abu Salmiya said. Other detainees released alongside Abu Salmiya also alleged abuse. The claims could not be independently confirmed but matched other accounts of Palestinians who have been held in Israeli custody. Abu Salmiya also said the medical staff at different facilities where he was held had taken part in the abuse “in violation of all laws” and that some detainees had limbs amputated because of poor medical care. There was no immediate response from the Israeli prison service, which has previously denied multiple similar accusations. The release of Abu Salmiya prompted a political row in Israel, with the country’s most senior officials denying prior knowledge of the move. Israel’s Shin Bet intelligence agency said it had decided on the release with the Israeli military “to free up places in detention centres”. The agency said it “opposed the release of terrorists” who had taken part in attacks on Israeli civilians “so it was decided to free several Gaza detainees who represent a lesser danger”. Itamar Ben-Gvir, Israel’s far-right national security minister, who controls the police and prison service, said the release of Abu Salmiya and others constituted “security negligence” and blamed the defence ministry, which denied responsibility. The opposition leader, Yair Lapid, said Abu Salmiya’s release was another sign of the government’s “lawlessness and dysfunction”. The row came as the Israeli army ordered another mass evacuation of Palestinians from much of Gaza’s second city, Khan Younis, in an indication that troops were poised to start a new ground assault on the city. Much of Khan Younis was destroyed in a long assault earlier this year, but large numbers of Palestinians have since returned to escape another Israeli offensive in Rafah, the southernmost city in the territory. Sporadic clashes continued in Rafah and elsewhere in Gaza on Monday, local people and officials said. The armed wing of Islamic Jihad, an Iranian-backed ally of Hamas, said it had fired rockets towards several Israeli communities near the fence with Gaza. The volley caused no casualties, the Israeli military said. Abu Salmiya was detained when Israeli forces raided al-Shifa hospital in November after alleging that Hamas had created an elaborate command and control centre inside the sprawling medical complex. The military uncovered a tunnel beneath the hospital leading to a few rooms, as well as other evidence that militants had been present inside the facility, but little that substantiated claims made before the raid that the complex concealed a sophisticated underground command base. The army raided al-Shifa a second time earlier this year, causing heavy destruction, after saying militants had regrouped there. Israel has raided several other Gaza hospitals after making similar allegations, forcing them to shut down or dramatically reduce services. Hospitals can lose their protection under international law if combatants use them for military purposes. Since the start of the war, Israeli forces have detained thousands of Palestinians from Gaza and the occupied West Bank, crowding military detention facilities and prisons. Many are being held without charge or trial in what is known as administrative detention. In May the Guardian reported allegations of widespread abuse at the Sde Teiman detention facility in the Negev desert in Israel’s south, based on whistleblowers’ accounts. Other media have also documented multiple descriptions of abuse at the camp, where thousands of detainees from Gaza have been held since the beginning of the war. Last month Israel’s high court of justice ordered the Israeli government to update it on conditions at the facility, after a legal petition from human rights organisations. Israel launched its offensive into Gaza after Hamas’s surprise attack into southern Israel in October, in which Palestinian militants killed 1,200 people, mostly civilians, and took another 250 hostage. The war has killed at least 37,900 Palestinians, according to Gaza’s health ministry. The figure does not differentiate between combatants and civilians but almost half of the 28,000 who have been fully identified were women and children.