Activists monitoring the situation say close to 50 people have been killed in ongoing air strikes in recent days.
Syrian opposition activists on Monday said that more air strikes and artillery shelling hit the northern city of Raqqa, the de facto capital of Daesh in Syria.
The Britain-based Syrian Observatory for Human Rights (SOHR) said that the city was pounded by war planes and artillery early in the morning on Monday. The activist group had no immediate word on casualties.
The YPG-dominated Syrian Democratic Forces (SDF) and the US-led coalition are attempting to drive Daesh from the city.
Air strikes have intensified over the past days as US-backed forces have marched toward the city, getting closer to besieging it from all sides. SDF is now reported to be about 3 kilometres (2 miles) from the city.
SOHR and activists in Raqqa say US-led coalition air strikes have killed close to 50 people in the past week.
Last week, SOHR said that that US-led air strikes on Syria killed 225 civilians between April 23 and May 23, the highest 30-day toll since the campaign against Daesh in Syria began on September 23, 2014.
According to SOHR, air strikes by the International Coalition have killed almost 8,000 combatants and civilians since they began operations against Daesh.
The International Coalition includes the United States, United Kingdom, France, Germany, Italy, Canada, and Denmark.