JERUSALEM (Reuters) - 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."

(Reporting by Lianne Back; writing by James Mackenzie, Editing by William Maclean)