The Islamic State group, previously known as the Islamic State of Iraq and the Levant (ISIS), on Tuesday defended its destruction of religious sites in the Iraqi city of Mosul on the grounds that the use of mosques built on graves amounted to idolatry, AFP reported.
"The demolition of structures erected above graves is a matter of great religious clarity," the jihadist group said in a statement posted on one of its main websites.
"Our pious predecessors have done so... There is no debate on the legitimacy of demolishing or removing those graves and shrines," the Islamic State said.
It cited the demolition by Mohammed bin Abdel Wahhab - founder of the puritanical Wahhabist brand of Islam followed by jihadists - of a dome erected above the tomb of Zaid ibn al-Khattab.
Khattab's reputedly heroic death on the battlefield earned him a posthumous following which Abdel Wahhab argued was tantamount to polytheism.
The Islamic State, which announced the restoration of the caliphate last month by declaring its sovereignty over land it has seized in Syria and Iraq, has levelled several of Mosul's most prominent religious landmarks.
They include the tomb of the Biblical Jonah, who is known as the paradigmatic example of teshuva (repentance) in the Bible, and the tomb of the Prophet Daniel.
Mosul's new jihadist rulers also threatened to blow up the so-called "hunchback" (Hadba), a leaning minaret built in the 12th century and one of Iraq's most recognizable landmarks.
The group insisted that all schools of Islamic law "agreed that using graves as mosques was un-Islamic" since it amounted to idolatry.