A new report is warning that children in Syria are experiencing 'toxic stress' and 'deep psychological scars' as a result of the ongoing war in the country.

The civil war in the country has been waging since 2011, and is believed to have led to more than 300,000 deaths.

Millions of people have also been displaced as a result of the conflict.

In their new report Invisible Wounds, the Save the Children charity says the impact of the war has increased many Syrian children's risk of substance abuse, depression, heart disease and suicide.

The group warns that children affected by regular airstrikes and violence live in a constant state of fear - which can result in 'toxic stress'.

According to Save the Children, these extreme stress levels "can have a life-long impact on children’s mental and physical health".

The 'psychological strain' has already manifested itself in many children, the report claims - with consequences such as involuntarily urination in public and serious speech impediments.

In a series of focus groups and interviews with more than 450 children, the charity found that 78% of the children feel grief and extreme sadness some or all of the time.

One child told the charity “I always feel angry, all the time", while another said “I would be confused if I didn’t hear or see airstrikes, because they happen so often".

Two-thirds of the children, meanwhile, are said to have lost a loved one over the course of the conflict.

Save the Children President and CEO Carolyn Miles said: "This is the result of six years of war, and is a tragedy that can’t be allowed to continue.

"We can end the toxic stress many children are suffering by stopping the bombardment of civilian areas and reaching everyone with lifesaving aid and psychological support."