UNITED NATIONS, June 29 (Xinhua) -- UN Secretary-General Antonio Guterres on Friday called for an immediate cessation of the ongoing military operations in southwestern Syria, expressing alarm by the offensive and its devastating civilian toll.

Speaking through his spokesperson Stephane Dujarric, Guterres recalled that the area is part of a de-escalation agreement reached between Jordan, Russia and the United States in Amman in July 2017, and called on its guarantors to uphold their commitments.

He called on all parties to respect their obligations under international humanitarian and human rights law, protect civilians and facilitate humanitarian access.

Particularly, he said all stakeholders must stop attacks directed against medical and educational facilities and put in place security conditions for UN cross-border humanitarian deliveries to resume.

The UN chief also urged the international community to jointly put an end to this expanding conflict, which risks further de-stabilizing the region and worsening the deep humanitarian crisis in Syria and neighboring states.

UN special envoy for Syria Staffan de Mistura has recently warned that a full-scale battle in the country's previously calm southwest could engulf an area and population the size of eastern Ghouta and Aleppo combined.

Also, the UN relief wing on Thursday put the number of displaced Syrians at 66,000 due to escalation in the southern part of the country, adding civilian deaths continue to be reported.