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BERLIN (Reuters) - German Chancellor Angela Merkel on Wednesday urged Iraqi Prime Minister Haider al-Abadi to investigate alleged human rights abuses that occurred during military operations to regain control of the city of Mosul from Islamic State militants.

Merkel telephoned al-Abadi to congratulate him on the victory of U.S.-backed Iraqi forces in Mosul, calling it a “big step forward in the fight against Islamic State,” her spokesman Steffen Seibert said in a statement.

The German leader also encouraged Abadi to investigate claims of human rights abuses that emerged after the military operations, Seibert said.

“Such human rights abuses must be prevented in the future,” Seibert said.

Amnesty International last week said that tactics used by Iraqi forces and their U.S.-led coalition allies in the battle for Mosul violated international humanitarian law and might amount to war crimes.

Another group, Human Rights Watch, said it had used satellite imagery to verify that a video published on Facebook that showed armed men in military uniforms beating a detainee before throwing him from a precipice and then shooting at him, had been filmed in west Mosul.

The footage also shows the men shooting at the body of another man already lying at the bottom of the precipice.

Reuters could not independently verify the footage. Since the victory announcement, security forces have severely restricted media access to west Mosul, saying they need to remove or defuse explosive devices.

(Corrects title of al-Abadi to prime minister, not president, in first paragraph)