Iraq's top Shi'ite cleric urged the forces battling to retake Falluja from Sunni militants Islamic State to spare civilians trapped in the city located just west of Baghdad.
Grand Ayatollah Ali al-Sistani added his voice to the many calls for restraint in the battle launched on Monday to recapture Fallujah, the first Iraqi city to fall under the control of the ultra-hardline Islamists, in January 2014.
"Sayyid Sistani reaffirms his recommendations that the ethics of jihad (Islamic holy war or struggle) be respected," his representative, Sheikh Abdul Mahdi al-Karbalai, said in a statement.
"Don't be extreme ... don't be treacherous. Don't kill an old man, nor a boy, nor a woman. Don't cut a tree unless you have to," he said, citing sayings of the prophet Mohammed.
Aid agencies have expressed mounting concern over the humanitarian situation in the city that has been under siege for some six months, and the United Nations has urged combatants to protect civilians escaping the fighting.
A large civilian death toll in the battle could further inflame sectarian tensions in Iraq which, since the fall of Saddam Hussein, a member of the Sunni minority, has been ruled by Shi'ites.
The Association of Muslim Scholars of Iraq, a hardline political organization formed in 2003 to represent Sunnis, has condemned the assault on Falluja as "an unjust aggression, a reflection of the vengeful spirit that the forces of evil harbor against this city".
Sistani wields enormous influence over Iraq's Shi'ites. It was at his call that Shi'ite militias regrouped two years ago in a coalition known as Popular Mobilization, or Hashid Shaabi, to stop the sweeping advance of Islamic State.