Watch: ISIS Destruction of Mosul's Grand Al-Nuri Mosque Shown in Night Vision Footage

Jaw-dropping footage of the moment the 12th century Grand al-Nuri Mosque is destroyed in the northern Iraqi city of Mosul emerged on Thursday, appearing to confirm that the Islamic State militant group (ISIS) was responsible for its destruction.

The complex, in the ISIS-controlled Old City of Mosul, is where the group's caliph Abu Bakr al-Baghdadi declared the Islamic State in July 2014.

The U.S.-led coalition announced that the structure was demolished late Wednesday, blaming ISIS. Iraqi officials also held the group responsible. The jihadi group, in an online statement, said an airstrike was to blame for its fall.

But night-vision footage obtained by CNN from the Iraqi military shows the building appear to implode from within. The leaning al-Hadba minaret can be seen in the distance, before the building explodes and black smoke and debris fill the city's panorama.

It represents another of ISIS's crimes against historic and ancient buildings and statues it considers to be idolatrous.

Iraqi Prime Minister Haider al-Abadi said the destruction of the mosque signaled that ISIS had conceded defeat in the city.

"Daesh's bombing of the al-Hadba minaret and the al-Nuri Mosque is a formal declaration of their defeat," Abadi said, using the Arabic acronym for ISIS.

The Iraqi coalition battling to oust the group from the largest city in its possession launched what it said was the final push to recapture the remaining areas under ISIS-control. The group has held on to the city for three years, implementing its brutal brand of ultraconservative Islam.

But the group is just weeks, perhaps days, from losing the territory it holds. One complication for advancing Iraqi forces is that some 100,000 people are estimated to remain in Mosul's Old City, being held as "human shields" by ISIS.

In another potential blow to the group, Russia said on Thursday that it had a high degree of certainty that it had killed ISIS caliph Abu Bakr al-Baghdadi in a May 28 airstrike.

RIA state news agency ran the ministry's claim, Reuters reported. Other state news outlets published the foreign ministry's claim that they have eliminated the most wanted man in the world.

"According to the Russian Defense Ministry, it is highly likely that Daesh leader al-Baghdadi was eliminated as a result of a Russian Aerospace Forces strike on the terrorists' command post in the southern suburb of the city of Raqqa in late May this year," Russian Deputy Foreign Minister Oleg Syromolotov told Russian state propaganda arm Sputnik.

The U.S.-led coalition said it could not confirm the reports. "We have no information to substantiate the Russian claims, but if true, it would be a great day for the people of Iraq and Syria brutalized by ISIS for the last three years under his brutal rule," a spokesperson said in an emailed statement to Newsweek.