ISIS destroys Tadmur prison, site of Assad regime atrocities

Militants of the Islamic State in Iraq and Syria (ISIS) blew up a major prison complex in the central Syrian city of Palmyra on Saturday, according to a group monitoring the war, destroying an important symbol of government control.

In another development, Syrian army airstrikes killed at least 70 people, most of them civilians, and wounded scores in attacks Saturday that struck civilian areas north of Aleppo, activists said.

Helicopters dropped explosives-filled barrels, one hitting the rebel-held Shaar neighbourhood in the city of Aleppo, killing at least 12 people, most of them from the same family. They included three children and four women, according to the Britain-based Syrian Observatory for Human Rights.

Busy market town bombed

The other attack hit a busy market known as Souk al-Hal in the ISIS-held town of al-Bab in Aleppo's countryside. The Observatory said at least 59 people were killed and dozens wounded, calling it the one of the worst massacres perpetrated by President Bashar al-Assad's army this year. It said the number of dead likely would rise because many of the wounded were in critical condition.

In Palmyra, the prison was empty at the time of the detonation, said Rami Abdulrahman from the Syrian Observatory for Human Rights. ISIS announced the explosion in a statement on social media and supporters posted pictures of huge clouds of grey smoke above the sprawling complex in the city, also known as Tadmur.

Syrian state media did not mention the explosion.

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The prison is not located among the city's ancient ruins, which Syrian officials have warned could be destroyed by the militant group, as have other ruins and countless artifacts. 

But ISIS fighters, who captured the city from government forces earlier this month, are not reported to have harmed its 2,000-year-old monuments and the prison explosion is the first report of major destruction since the takeover.

It was the first time that ISIS wrested control of a city held by the Syrian government forces, rather than rebel groups. 

The Observatory said this week ISIS had shot to death around 20 men in the city's ancient amphitheatre, accusing them of being pro-government.

It was not immediately clear when the prisoners had left their cells. Pictures posted by ISIS fighters on social media this week had purported to show empty cells, a collective detention room and a management office inside the prison.

'Maximum suffering'

Detailed information about inmates and conditions inside the high security prison is rare.

A 2001 Amnesty International report, based on the accounts of former inmates, described the prison as "designed to inflict the maximum suffering, humiliation and fear on prisoners."

It said Lebanese, Palestinians, Jordanians, and Iraqis were also believed to have been detained in Syrian prisons, including in Palmyra.

Former war crimes prosecutors said in January 2014 that a Syrian military police photographer had supplied evidence showing the systematic torture and killing of about 11,000 detainees in Syrian jails. The Syrian government said the images were fake, though they were verified by a number independent sources.