The U.S.-led coalition bombing Syria has killed hundreds of civilians, including children, according to the Syrian Observatory for Human Rights.


Hundreds of Syrian civilians have been killed by U.S.-led airstrikes over the past 14 months, a human rights monitor said Monday.


In total, 250 civilian deaths have been recorded since September 2014 by the Syrian Observatory for Human Rights (SOHR), according to Al Jazeera. Overall, the year-old airstrike campaign has killed almost 4,000 people, including militants from the Islamic State group, SOHR was cited as reporting by Al Jazeera.


The monitor said the dead included more than 60 young children.


The U.S. military has admitted to just six civilian casualties from its airstrikes in Syria and Iraq. Most recently, the U.S. Central Command said last week an investigation into four civilians who were killed during a strike on the Iraqi city of Hatra.


In May, a separate military investigation concluded two children were killed in a November 2014 airstrike in Syria.


The United States has led a campaign of aerial bombardment in Syria since late 2014, mostly claiming to be targeting the Islamic State group. In a single bombardment in March, 30 civilians were killed when U.S.-led forces targeted an oil refinery in a region of Syria controlled by the Islamic State group, according to a SOHR report.


Syria has been in a state of civil war for over four years. The conflict has left over 200,000 dead, and displaced over 7 million people.