"There are systematic strikes on hospitals, White Helmet offices and schools," Raed al-Saleh told AFP in an interview in Paris, ahead of a meeting with French foreign ministry officials.

Saleh has been visiting European capitals ahead of a visit to Washington to push for a flight embargo as violence escalates in Syria's nine-year-old civil war.

Nearly one million refugees have fled Idlib towards Turkey since December, when Russia-backed Syrian forces launched an offensive against the last rebel holdout.

"Russia's decision to pursue a military campaign proves that the political solution they were talking about was not realistic," Saleh said.

"The situation is truly catastrophic," he said. "We have 200,000 people without any shelter, they are sleeping on sidewalks or in their cars."

On Sunday, Turkey confirmed a full military operation in northwest Syria after an air strike on Thursday blamed on Damascus killed 34 Turkish soldiers.

Yet Saleh said that had not brought any respite for civilians and refugees still in Idlib. "As long as there is fighting and airstrikes, it just doesn't stop," he said.

The White Helmets began operating in 2013 by rescuing people from homes and other buildings hit in Syrian areas held by opponents of President Bashar al-Assad.

Saleh said the group's 2,950 volunteers now also focus on evacuating civilians and establishing refugee camps,

"We don't know what's going to happen -- Is NATO going to take a position? Are the United States or other countries going to react? Is Russia going to strike Turkish forces?"

"All these things could change the situation. But if the international community does not respond, in particular to address the humanitarian crisis, I think everybody will pay the price," he said.