Paris: French authorities have launched a probe against the regime of Syrian President Bashar al-Assad for alleged crimes against humanity committed between 2011 and 2013, a judicial source told AFP on Tuesday.

Paris prosecutors opened a preliminary inquiry on 15 September, the source said.

The investigation is drawing in particular on evidence provided by a former Syrian military police photographer, who fled the country in 2013, bringing with him some 55,000 graphic photographs of scenes from the brutal conflict.

‘Faced with these crimes that offend the human conscience, this bureaucracy of horror, faced with this denial of the values of humanity, it is our responsibility to act against the impunity of the assassins,’ French Foreign Minister Laurent Fabius said in a statement sent to AFP.

While Assad is unlikely to ever take the stand in a French court, the inquiry could add to political pressure on the Syrian leader in the midst of a diplomatic row between the West and Russia and Iran over his fate.

The Syrian conflict has taken centre-stage at the United Nations General Assembly, where US President Barack Obama and his Russian counterpart Vladimir Putin have clashed over how to bring an end to Syria’s civil war.

On Tuesday the US leader said removing Assad was a vital step to defeating the Islamic State group, which has taken advantage of the chaos in Syria to bring large parts of the country and neighbouring Iraq under its rule.

Syria’s four-year was has killed more than 240,000 people and Western diplomats have accused Damascus of killing more Syrians than IS by dropping barrel bombs -- charges the government denies.

The brutal conflict has also displaced millions of people, a key driver behind Europe’s refugee crisis. 

Paris’s investigation is focusing on evidence from a former Syrian army photographer known by the codename ‘Caesar,’ who defected and fled the country in 2013, bringing with him some 55,000 graphic photographs.

They show people with their eyes gouged out, emaciated bodies, people with lesions on the back or stomach, and also a a picture of hundreds of corpses lying in a shed surrounded by plastic bags used for burials.

Entitled ‘Assad’s secret killings,’ the dossier is being used by international bodies including the UN as part of an investigation into the regime’s role in ‘mass torture’.

The Syrian government has branded the report ‘political’.

These ‘thousands of unbearable photos, authenticated by many experts, which show corpses tortured and starved to death in the prisons of the regime, demonstrate the systematic cruelty of the Assad regime,’ Fabius told AFP.

The inquiry will be led by France’s war crimes body but Fabius also called on the UN and particularly its International Commission of Inquiry on Syria to press on with their investigations.