At least 500 inmates – most of them “senior” Al Qaeda terrorists – have escaped from two jail in Iraq, threatening to worsen the security situation in a country rocked by sectarian and political violence.

The jailbreaks occurred in Taji, to the north of the capital Baghdad, and west of the capital, in the infamous Abu Ghraib prison, according to the BBC.

Abu Ghraib gained notoriety in 2004 when evidence surfaced of abuse against Iraqi inmates by US forces. It was previously used as a prison by Saddam Hussein’s regime, where political opponents were systematically tortured.

Attackers used mortar shells and suicide bombers to free the prisoners, killing at least 20 members of the Iraqi security forces.

At a press conference, Interior Minister Wissam al-Firaiji claimed that twelve suicide bombers were involved in the assault on Taji jail alone, including three driving “car bombs.”

He also said that attackers fired more than 100 mortar shells, and claimed that “the situation is now under control.”

Iraqi authorities initially denied that any inmates had escaped, claiming to have repelled the attack. They were soon forced to backtrack as it became clear that around 500 senior Al Qaeda operatives – many of them on death row for deadly attacks – had in fact been freed.

Iraq is in the throws of serious sectarian and political violence – between its Shia and Sunni populations, as well as between political rivals within the government. This latest development will come as a severe blow to security forces as they seek to combat those groups – including Al Qaeda – who are responsible for much of the violence.

During the past 2 years, many Iraqi Al Qaeda terrorists have relocated to Syria to fight in the bloody civil war there as part of the Islamic State of Iraq and al-Sham (ISI) – an Al Qaeda franchise which seeks to replace the regime of Bashar al-Assad with an “Emirate” ruled by Islamic law.

It is not yet known how this injection of hundreds of seasoned Al Qaeda fighters will impact the conflict there.