PARIS (Reuters) - France’s foreign minister said on Wednesday that the indiscriminate bombing of Syria’s Idlib region by Russian, Syrian and Iranian forces could amount to war crimes.

French Foreign Minister Jean-Yves Le Drian attends the questions to the government session at the National Assembly in Paris, France, September 12, 2018. REUTERS/Gonzalo Fuentes

“The hypothesis of war crimes can not be excluded ... once one begins to indiscriminately bomb civilian populations and hospitals,” Jean-Yves Le Drian told lawmakers.

An estimated 3 million people live in Idlib - the last major stronghold of active opposition to President Bashar al-Assad. Assad has vowed to retake the province, backed by his Russian and Iranian allies.

Syrian government and Russian warplanes began air strikes in Idlib last week in a possible prelude to a full-scale offensive and aid organizations said several medical facilities have already been targeted.

It is not the first time France has warned Assad, Russia or Iran that their aggression could amount to war crimes.

In 2016, the government of former president Francois Hollande said it was working to find a way for the International Criminal Court’s prosecutor to launch an investigation into war crimes that it believed had been committed by Syrian and Russian forces in eastern Aleppo.

Little came from the French initiative as the court has no jurisdiction for crimes in Syria since Damascus has not signed up to the Rome treaty establishing the ICC.

The ICC could investigate, however, through a U.N. Security Council referral. But the council has been deadlocked over Syria for years. Moscow vetoed a French resolution in May 2014 to refer the situation in Syria to the ICC.

French officials were not immediately available to comment on whether Paris planned a new push at the ICC.

“The situation is extremely serious. We are on the eve of a considerable humanitarian and security catastrophe,” Le Drian said.

He said that efforts should be made immediately to prepare for a mass humanitarian crisis should thousands of people be displaced by the fighting.