Activists inside Syria have revealed that an ISIS fighter has executed his own mother in Raqqa after he reported her for trying to persuade him to leave the jihadi group.

The sickening act was witnessed by a large crowd in front of the postal building inside the ISIS stronghold in Syria, according to activist group Raqqa is Being Slaughtered Silently.

Ali Saqr al-Qasem used an assault rifle to execute his mother Lena, 45, after she was found guilty of apostasy.

The London-based Syrian Observatory for Human Rights have revealed that Ms al-Qasem was also accused of trying to persuade her son to abandon ISIS and flee Syria with her.