JERUSALEM - Israeli Prime Minister Benjamin Netanyahu said on Monday an air strike in the area of Rafah in southern Gaza that killed dozens of Palestinians was not intended to cause civilian casualties and would be investigated.

"In Rafah, we already evacuated about 1 million non-combatant residents and despite our utmost effort not to harm non-combatants, something unfortunately went tragically wrong," he said in a speech in parliament that was interrupted by shouting from opposition lawmakers.

"We are investigating the incident and will reach conclusions, because this is our policy."

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An Israeli government spokesperson said that initial reports show a fire broke out after the strike, killing civilians.

Also on Monday, Israeli armed forces' chief prosecutor said Israel is investigating the deaths of Palestinians captured during the Gaza war as well as a military-run detention camp where a human rights group has alleged abuse of inmates

"According to initial reports, these are initial reports, a fire broke out after the attack which appears to have taken civilian lives. Civilian casualties are desperately sad, but this is the war Hamas wanted and started," said government spokesperson Avi Hyman.

He did not elaborate on the reports. Israel's military said earlier it was investigating the incident.

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Also on Monday, Israeli armed forces' chief prosecutor said Israel is investigating the deaths of Palestinians captured during the Gaza war as well as a military-run detention camp where a human rights group has alleged abuse of inmates.

Citing accounts by former inmates and a doctor from the Sde Teiman base, the Physicians for Human Rights group said last month that detainees have suffered severe violence causing fractures, internal bleeding and even death.

Palestinians have also accused Israeli soldiers of illegal killings during the almost eight-month-old Gaza war.

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"To date, 70 military police investigations have been opened into incidents that have raised suspicion of criminal offenses," Major-General Yifat Tomer Yerushalmi, the military advocate-general, told a conference hosted by the Israel Bar Association.

"These investigations also address allegations raised about the incarceration conditions at Sde Teiman detention center and the deaths of detainees in IDF custody. We are treating these allegations very seriously and are taking action to probe them."