The 16-month uprising centred on ousting Syrian President Bashar al-Assad has been formally declared a civil war by the Red Cross.
The Red Cross had previously designated Idlib, Homs and Hama as war zones, but the change in status means international humanitarian law applies wherever fighting occurs throughout the country.
According to The Telegraph, combatants will now be officially subject to the Geneva Conventions, and will be more exposed to war crimes prosecutions, after the International Committee of the Red Cross declared that the conflict was a 'non-international armed conflict', or in lay terms a civil war.
The categorisation was made after the ICRC determined that the armed opposition to Assad's regime had reached a sufficient level of organisation and capability.
The Syrian Observatory for Human Rights reported heavy clashes in Damascus in what was described as the 'most intense' fighting there since the start of the uprising.
The paper quoted Sean Maguire, a spokesman for the ICRC, as saying that both sides would be reminded of their obligations 'to protect civilians from fighting, treat the wounded and sick without discrimination'