New photos show Islamic State (Isis) militants using a ruler to measure out the exact size of the wound that will be inflicted on a young man.

This is part of the terror group's sadistic policy of "eye-for-eye" criminal penalties, in which the militants inflict the same injuries on alleged criminals that they supposedly inflicted on their victims.

In this particular case, the two men being harmed were accused of beheading a man in the city of Mosul in Iraq.

The images were posted online by anti-Islamic State activists Raqqa is Being Slaughtered Silently (RIBSS), which oppose the militants' brutal practices.

Blood is dripping from a boy\'s head
Blood is seen dripping from the young man\'s head, as he is punished for beheading another man in Mosul Source: RIBSS

Islamic State has shared thousands of photos taken within land under its control, revealing its merciless interpretation of law and order.

The group has also published a list of penalties for alleged crimes committed under its territory. It claims the punishments are based on Sharia law.

Adulterers who are involved in sexual relationships are stoned to death, while those found guilty of "highway robbery" face execution.

IS believes that this list of religious punishments is a "warning and deterrent" to so-called disbelievers and infidels. Many of the punishments are already practised by IS.

Public crucifixions in the IS stronghold of Raqqa in northern Syria have become more common, while pictures of stonings and homosexuals being thrown from buildings have been widely circulated on the internet and forms of social media.