The suburb, 15km east of Damascus has an estimated population of 400,000, who have been under siege since 2013.

Eastern Ghouta, located just east of Damascus, has become the recent focus of a fierce offensive by Syrian President Bashar al-Assad's forces.

In just over a week, more than 500 civilians have been killed, according to the UK-based Syrian Observatory for Human Rights.

The rebel-held enclave, which was besieged by the government in 2013, is home to about 400,000 people.

READ MORE: Syria civil war map - who controls what?

On February 24, the UN unanimously approved a resolution calling for a 30-day ceasefire in Syria. Hours later, Syrian government forces launched a ground and air offensive on the Damascus suburb.

Health officials have also accused the Syrian government of using chlorine gas in their aerial bombardment campaign on Eastern Ghouta.

The UN has called the situation in the enclave "hell on earth".

Hundreds of thousands of people have died in fighting during Syria's seven-year civil war, and millions have been forced to flee the country.