US-led coalition jets bomb Syrian school housing refugee families

US-led coalition fighter jets have bombed a school used as a refugee reception centre killing at least 33 people, a monitor said on Wednesday. 

Air strikes hit the refugee centre close to the Islamic State group-held town of al-Mansoura, Raqqa province, in the "early hours of Tuesday" according to the monitor.

Syrian activists said that some 150 people were killed in the attack, and that the hike in civilian deaths is due to the US military relaxing its rules of engagement.

It comes as coalition planners are due to meet in Washington on Wednesday to hear more about US President Donald Trump's plan to defeat IS.

It also comes amid growing civilian casualties from US air raids in Syria, and concerns the Pentagon's plans for erradicating the group will lead to many more deaths.

The school-turned-shelter, hit early on Tuesday morning, lies 20 miles from Raqqa.

It was likely a targeted by US jets looking to clear a path for Washington-backed Syrian Democractic Forces who are preparing for an assault on IS' self-declared capital.  

"We can now confirm that 33 people were killed, and they were displaced civilians from Raqqa, Aleppo and Homs," Rami Abdel Rahman from the Syrian Observatory for Human Rights told AFP. 

"They're still pulling bodies out of the rubble until now. Only two people were pulled out alive." 

Syrian activist group Raqqa is Being Slaughtered Silently said the centre was home to some 50 displaced families.

Syrian regime media, meanwhile, blamed US air strikes for killing dozens of casualties and destroying the school.

Officially, the coalition has said that at least 220 civilians have been killed in air strikes but the real figure is believed to be much higher. 

The lion's share of the some 500,000 deaths in the Syria war - the vast majority civilians - have been killed by regime forces.