The London based Syrian Observatory for Human Rights (SOHR), said 3,207 have been killed in that war-torn country.

Another 7,700 were executed in Iraq, according to the Iraqi Observatory for Human Rights, which tracks ISIS violations.

The soldiers and civilians who have been beheaded, shot dead, drowned, blown up, stoned to death and thrown off buildings for violating ISIS's twisted laws all contributed to this mammoth death toll.

The figure does not include the thousands more who have been killed in battle and suicide bombings - or the innocent people mown down by ISIS extremists as they tried to flee.

SOHR said 1,858 of those executed by ISIS in Syria were civilians. Of these, 98 were women and 76 were children under the age of 18.

This number does not take into account the dozens of young boys who have been forced to carry out suicide bombing missions.

ISIS has also executed 239 rebel fighters and 185 Its fighters, SOHR claimed.

Meanwhile, the Iraqi Observatory of Human Rights (IOHR) said 7,700 people have been executed in the country during the same time.

Around 2,100 of these were in the ISIS stronghold of Mosul and 1,900 in the Al-Anbar governate which ISIS largely seized in May.

Another 250 executions took place in Diyala where the group has an established base of operations and 110 in Kirkuk where it has been clashing with Iraqi Peshmerga forces.

SOHR claimed the others came in various other ISIS-held territories throughout the country. It also said around 40 percent of those executed were civilians.