Iraq's top Shiite cleric has called on the government in Baghdad to do all it can to protect the families of Iraqi forces fighting the Islamic State group, saying they are an "easy prey" for extremists bent on revenge attacks.

In his Friday sermon, Ayatollah Ali al-Sistani also said authorities should implement tough policies to catch and punish those who attack innocent civilians.

Al-Sistani's appeal comes amid mounting pressure on the government to catch and prosecute those responsible for last week's massive bombing in eastern Diyala province that killed 115 people as the Islamic holy month of Ramadan was coming to an end.

Many women and children were among the victims in the predominantly Shiite district of Khan Bani Saad.

The Islamic State group has claimed responsibility for that attack.