Gaza's Crossings Authority said Israel released dozens of Palestinian detainees into the territory on Monday, alleging mistreatment which the Israeli military denied.

Israeli soldiers have rounded up hundreds of Gazans during their more than six-month war against Hamas militants in the territory, holding them without charge before releasing some in groups.

"Since the early hours of the morning, 150 prisoners from various parts of the Gaza Strip who were detained by the Israeli occupation have been released," via the Kerem Shalom border crossing, according to Crossings Authority spokesman Hisham Adwan.

"It is very noticeable that there is severe mistreatment of these prisoners, as a number of them were sent to Abu Yousef al-Najjar Hospital for treatment" in Rafah, a city in Gaza's far south, he added.

One of those released on Monday told AFP he and a friend were beaten and tortured in Israeli detention.

AFP is not publishing his name for his safety.

"I remained on my knees for (almost two months), from five in the morning until 10 at night, blindfolded and with tied hands," he said.

"The army... released dogs on us to attack us," he added. "They beat and tortured us."

The Israeli military did not comment on the release of these detainees but said the mistreatment of those in detention was "absolutely prohibited".

"Those who are not involved in terrorist activity are released back to the Gaza Strip," it told AFP in a statement.

Last month, the Gaza Crossings Authority said 56 Palestinian detainees released from Israeli prisons "showed signs of torture" committed during their detention. Israel's military said at the time that detainees "are treated under international law".

Also last month, the head of the UN's Palestinian refugee agency, Philippe Lazzarini, said Gazans held by Israeli forces have come back "completely traumatized" upon release and reported abuses while in captivity.

He said Gazans detained by Israel reported "a broad range of ill-treatment" including threats of electrocution, being photographed naked, sleep deprivation, and having dogs used to intimidate them.

In January, the United Nations human rights representative in the Palestinian territories said thousands of Gazan men may have been detained by Israeli forces since war erupted on October 7, often facing conditions that could amount to torture.