Speaking at a news conference in the Syrian capital, Guterres delivered a warning of foreign military activity, calling breaches of Syrian sovereignty and territorial integrity "unacceptable."

He urged Israel to comply with the 1974 Disengagement Agreement, which established a buffer zone along the Golan Heights following the Yom Kippur War.

The UN chief's high-level visit included a tour of Sednaya Prison, the detention facility north of Damascus.

Guterres said inspecting the site exposed the horrific scale of systematic atrocities carried out under former president Bashar al-Assad, where tens of thousands of victims were tortured and executed.

Guterres stressed that the harrowing visit underscored the urgent need for transitional justice and full accountability for past atrocities.

He expressed confidence in Syria's ongoing political transition following the fall of the Assad government, stating that the international process is moving in the right direction.

In addition to security concerns, the UN leader sounded a severe warning over a deepening humanitarian crisis.

International assistance currently meets only about 20 percent of the Syrian population's basic needs, leaving a massive funding shortfall that jeopardizes national recovery after more than a decade of war.

Commending the endurance of the population, Guterres noted that years of hardship and mass displacement have not broken the resolve of Syrians to pursue their "legitimate aspirations."

He reaffirmed the United Nations' full commitment to supporting Damascus through one of the most critical political shifts in its modern history.