Baghdad - Most of the Mosul Museum's collection was transferred to Baghdad's National Museum for safekeeping six months before fighters with the Islamic State of Iraq and the Levant (ISIL) took over the city of Mosul in June 2014, according to Iraqi archaeologists.

"Early last year, 1,700 out of the 2,200 artefacts that make up the museum collection, were transferred to Baghdad for safekeeping and because there was maintenance work in [the] museum building," Abdullah al-Jumaili, an archaeology professor and adviser to the Mosul Museum, told Al Jazeera. By the time ISIL fighters raided the museum, there were only 300 pieces left, he noted.

The Mosul Museum is the second largest museum in Iraq, after the National Museum in Baghdad. Last week, stunning video footage emerged that showed ISIL fighters destroying some of Iraq's priceless artefacts in the Mosul Museum and several other sites in Nineveh. The UN's representative in Iraq described the rampage as "barbaric".

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According to Iraqi archaeologists, Mosul has the majority of Iraq's archaeological wealth, with more than 3,500 sites - including centuries-old religious and historic sites. The Mosul Museum consists of four halls: the Assyrian hall, the Hatrene hall (Hatra was a wealthy trading city established centuries ago, with its traces found 110km southwest of Mosul), the Islamic hall, and the Prehistoric hall.

After analysing a YouTube video of the destruction posted by ISIL, museum officials recognised that it took place in two of the four halls: the Assyrian and the Hatrene halls. "There were no scenes from the Islamic antiquities hall and the Prehistoric hall that was almost empty," Jumaili told Al Jazeera.

The Islamic hall, according to Jumaili, included many priceless antiquities.

ISIL deliberately filmed while they were destroying the pieces, but we do not believe that they really did. They [ISIL] were breaking the big pieces, which would be difficult to transfer from one place to another. We believe that they have been smuggling these antiquities to Turkey and Syria. Aamir Abdullah al-Jumaili, adviser to Mosul Museum

"The majority of pieces were original and only four or six gypsum sculptures were shown in the video they broadcasted, and the sculptures supposedly destroyed belonged to the Assyrian and Hatrene periods," Jumaili told Al Jazeera.

The video shows that ISIL partially or totally smashed many Assyrian and Hatrene sculptures, including one of a Hatrene king holding an eagle alongside three other Hatrene statues, representing four of the 27 Hatrene statues that Iraqi archaeologists excavated.

Archaeologists say the damage ISIL inflicted on the legacy of Hatra was "catastrophic". But some media reports questioned whether the sculptures ISIL smashed might have been fake.

According to Jumaili, those who say the sculptures were mainly gypsum are either "trying to cover up for ISIL's crimes or underestimate the disaster".

In a recent interview, Mosul's exiled governor, Atheel Nujaifi, pointed out that two of the items shown in the video as being destroyed by ISIL fighters were genuine, including the Winged Bull and the God of Rozhan. Some genuine items were missing in the video, Nujaifi said, which shows that "ISIL took at least seven items before destroying the museum. They also destroyed the items that they were not able to take with them."

Jumaili and other archaeologists say the destruction scenes raise questions about the real motives behind the video. Jumaili believes it was staged to show that ISIL smashed the statues, when in reality they looted them.

"ISIL deliberately filmed while they were destroying the pieces, but we do not believe that they really did," he said. "They [ISIL] were breaking the big pieces, which would be difficult to transfer from one place to another. We believe that they have been smuggling these antiquities to Turkey and Syria."

Jumaili lamented the fact that parts of the Assyrian hall were sacrificed to save the contents of the Hatrene and Islamic halls.

"ISIL militants are working to convince the world that Arabs are not capable of safekeeping these antiquities and that westerners are the right people to do so," he said.

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Iraqi archaeologists acknowledge that since last June, when ISIL took over the city of Mosul, its fighters have looted and damaged more than 42 sites, including mosques, churches, shrines, and libraries. Most of these sites were mosques and shrines that belonged to the Abbasid era and churches that were centuries old. Some of the most important included the Castle of Tal Afar, the mosque of Prophet Jonah, the mosque of Prophet Sheet, the mosque of Prophet Zarzis, al-Tahera (the Pure) Church and the Virgin Mary Church.

These sites contained prophets' and saints' tombs, as well as donation money, vows and offerings, Jumaili said. "All this has been looted by ISIL before they were bombed," he suggested.

According to Jumaili, the biggest nightmare for Iraqi archaeologists has been that ISIL would target Nineveh and its gates - the remains of the Assyrian capital.

On Friday, that nightmare came true as ISIL fighters looted and bulldozed the ancient Assyrian city of Nimrud, established in 13th-century BC.

Jumaili and other archaeologists have headed to Baghdad to resume work in the National Museum and "wait until the government decides on the next step", he said.

"I wished it was a nightmare and I will wake up to find everything is OK, but that did not happen, and it was real," he said. "What I was afraid of, just happened."