He stressed that all parties are obliged under international law to distinguish between lawful military targets and civilians and civilian objects.

Since Dec. 31, at least 85 civilians, including 21 women and 30 children, have been killed and at least 183 injured in Eastern Ghouta, where at least 390,000 civilians have been living under siege for four years, according to information gathered by the Office of the UN High Commissioner for Human Rights (OHCHR).

On Tuesday, airstrikes and ground-based strikes hit a residential area in opposition-controlled Hamourya, reportedly killing at least 13 civilians. The previous day, two airstrikes and simultaneous ground-based strikes on a residential area near a market in the opposition-held town of Duma reportedly killed 12 civilians.

Armed opposition groups also continue to fire rockets into residential areas in government-controlled Damascus. On Jan. 4, a rocket fired into Old Damascus hit the vicinity of a bakery, reportedly killing a woman and injuring 13 other civilians.

The High Commissioner also noted that the failure to evacuate urgent medical cases from Eastern Ghouta runs contrary to its international humanitarian law obligations to collect, care for, and take measures to evacuate the sick and wounded.

In Idlib, ground attacks and airstrikes have escalated as a rapidly-moving government offensive gains momentum, jeopardizing the safety of hundreds of thousands of civilians, said Zeid, noting that an explosion on Jan. 7 reportedly killed 28 civilians.