The Islamic State terror group executed and crucified a man in Syria's northern Aleppo province before hundreds of residents, accusing him of apostasy for refusing to join prayers at a mosque, according to local reports.

The 28-year-old victim, identified as Hussein Muhammad, was arrested by Islamic State's religious police in the city of al-Bab before being charged by a Sharia court, according to ARA News.

"A Sharia judge decided to execute and crucify the man in public, claiming he was an apostate who refused to perform Sharia duties and violated the basic laws of the Caliphate," an anonymous source was quoted as saying.

Muhammad was first shot to death on Thursday, and then his body was hung on an electricity pole for everyone to see.

"The victims' body will remain crucified for three days, and ISIS threatened people that anyone who would try to remove him will be mercilessly punished," an activist was quoted as saying.

The London-based Syrian Observatory for Human Rights says it has documented more than 2,353 executions of Syrian civilians during 25 months since the terror group declared its alleged caliphate.

Islamic State, also known as ISIS, ISIL or Daesh, is an offshoot of al Qaeda, and wants to establish a caliphate in the Levant region and beyond.

While the Sunni terror group is losing territory in Iraq and Syria, it still has 18,000 to 22,000 fighters there despite some 13,000 airstrikes by the international coalition led by the United States, according to CIA director John Brennan.

The group uses brutal methods to torture and punish those who it considers to be its enemies, including Muslims who do not believe in its version of Islam. However, Christians and other minorities are among its main targets.

In its English propaganda publication, ISIS last year sought to justify its barbarity, saying it is "Islamic" to capture and forcibly make "infidel" women sexual slaves.

"Before Shaytan [Satan] reveals his doubts to the weak-minded and weak hearted, one should remember that enslaving the families of the kuffar [infidels] and taking their women as concubines is a firmly established aspect of the Shari'ah that if one were to deny or mock, he would be denying or mocking the verses of the Qur'an and the narration of the Prophet … and thereby apostatizing from Islam," stated the IS' propaganda magazine "Dabiq."