Pope Francis on Sunday warned of a “human catastrophe” in the Syria’s Idlib province, the last major rebel bastion which is being shelled by government forces.

President Bashar al-Assad’s forces have been amassing along Idlib’s borders for weeks and shelling rebel-held territory on a daily basis, according to the Britain-based Syrian Observatory for Human Rights.

The pontiff said there were still “winds of war” and “unsettling news about the risk of a possible humanitarian catastrophe in the province of Idlib.”

Speaking during Angelus prayers, the pope urged the international community and other actors “to make use of the instruments of diplomacy, dialogue and negotiations, in compliance with international humanitarian law and to safeguard the lives of civilians.”

Idlib is adjacent to Latakia province, the coastal heartland of Assad’s Alawite minority and home to the Russian military airport of Hmeimim.

In recent days, Damascus and Moscow have stepped up warnings of an imminent assault on the province, which shares a border with Turkey and is dominated by Hayat Tahrir al-Sham, a jihadist alliance led by the former branch of Al-Qaeda in Syria.