BAGHDAD • Abu Omar Al-Shishani, whom the Pentagon described as "minister of war" for terrorist group Islamic State in Iraq and Syria (ISIS), was killed in combat in the Iraqi city of Shirqat, south of Mosul, a news agency that supports the militant group said yesterday.

The Pentagon said in March that Shishani had likely been killed in a US air strike in Syria, but this was the first time the group appeared to confirm his death. Reuters could not independently verify the statement from Amaq news agency, which ISIS regularly uses to issue reports and which denied Shishani's death after the Pentagon's comments in March.

ISIS supporters exchanged notes of praise and condolence on social media, including pictures of the ginger-bearded fighter, and pledged to launch a fresh offensive in his honour.

Officials at the Pentagon said they were aware of yesterday's report but could not confirm or deny it.

Mr Hisham Al-Hashimi, a Baghdad-based security expert who advises the Iraqi government, said a source in Shirqat had confirmed that Shishani had been killed there along with several other militants.

Iraqi forces are advancing towards Mosul, the largest city still under the control of ISIS. They have mostly surrounded Shirqat, 250km north of Baghdad, and last week retook a major airbase from the militants to use in the main push on Mosul, 60km further north.

But Mr Rami Abdelrahman, head of the British-based Syrian Observatory for Human Rights, said Shishani had been wounded in March and died soon after in the countryside east of Raqqa.

"I confirmed with the doctor who went to see him," said Mr Abdelrahman, who tracks the war in Syria through a network of contacts. He told Reuters that ISIS likely delayed announcing his death to allow time to line up a successor.

Shishani, also known as Omar the Chechen, ranked among America's most-wanted militants under a US programme that offered up to US$5 million (S$6.7 million) for information to help remove him from the battlefield.

Born in 1986 in Georgia, Shishani had a reputation as a close military adviser to ISIS leader Abu Bakr Al-Baghdadi, who relied heavily on him, according to followers.

Shishani once fought in military operations as a rebel in Chechnya. He joined Georgia's military in 2006 and fought against Russian troops before being discharged two years later for medical reasons, according to US officials.

He was arrested in 2010 for wea- pons possession and spent more than a year in jail before leaving Georgia in 2012 for Istanbul and later Syria.

He joined ISIS the following year and pledged his allegiance to Baghdadi. The US State Department said Shishani was identified as ISIS' military commander in a video distributed by the group in 2014.

REUTERS