The U.N.'s special envoy to Syria has arrived in Damascus to meet with Foreign Minister Walid al-Moallem amid an intensified government campaign in Aleppo that has left all hospitals in the city's opposition-held districts out of service.

U.N. Envoy Staffan De Mistura and al-Moallem are expected to hold a press conference Sunday afternoon.

De Mistura warned in an interview with the U.K. newspaper The Guardian earlier this week that the government was chasing a "phyrric victory" in Aleppo if the government does not arrive at a political settlement with the opposition

He warned the that military's unrestrained approach would drive more moderate rebels into the ranks of the Islamic State group.

The pro-government Al-Watan newspaper reported Damascus's displeasure with De Mistura's comments ahead of Sunday's meeting.