By Saif Hameed

BAGHDAD (Reuters) - Iraq's prime minister fired three officials in charge of Baghdad's security on Friday after last weekend's bombing that killed nearly 300 people and caused public outrage over the inadequacy of the emergency services and security apparatus.

The bombing, claimed by the ultra-hardline Sunni militant group Islamic State (IS), was the deadliest in Iraq since U.S.-led forces toppled Saddam Hussein 13 years ago.

Islamic State has lost ground since last year to U.S.-backed government forces and Iranian-backed Shi'ite Muslim militias advancing into territories they control in northern and western Iraq, but IS retains the ability to strike the heart of Baghdad.

A statement posted on Prime Minister Haider al-Abadi's Facebook page said he had dismissed the commanders of military operations, security services and intelligence in the capital.

"The sacking of the Baghdad Operations Commander was due to accumulated mistakes that cannot be overlooked," one senior security official said, speaking on condition of anonymity.

"It is a difficult decision and came at a critical time because we are engaged in a tough battle with Daesh, but it had to be made because of the catastrophic failure," he said. Daesh is a derogatory Arabic acronym for Islamic State.

The commander of the Joint Operations Command, General Talib Shaghati al-Kenani, has been put in temporary charge of security in the capital, the security official said. The Joint Operations Command coordinates Iraqi armed forces and U.S.-led coalition air support used in military operations against Islamic State.

The official said the bombing was clear evidence of the weakness of the security apparatus in Baghdad.

"The car bomb came from outside the capital, crossing dozens of checkpoints before reaching the target. All of them answer to the operations command," he said.

Interior Minister Mohammed Ghabban resigned on Tuesday, after blaming the bombing on a lack of communication between the various forces in charge of security in Baghdad.

Abadi approved Ghabban's resignation on the same day he tendered it, according to a statement on the premier's website.


Iraq's top Shi'ite cleric, Grand Ayatollah Ali al-Sistani, on Friday criticized the Abadi government's failure to deal effectively with the threat Islamic State poses.

"Complacency among corrupt and failed (officials) at the expense of the blood and souls of innocent civilians is unbearable and needs to be stopped," he said in his weekly sermon, read on his behalf in the Shi'ite holy city of Kerbala, south of Baghdad.

Islamic State also claimed a triple suicide attack late on Thursday near a Shi'ite mausoleum north of Baghdad that killed at least 35 people, according to security sources.

Baghdad-based security analyst Hisham al-Hashimi said this attack made an escalation of sectarian strife highly likely.

Shi'ites form a majority in Iraq but northern and western provinces are mostly Sunni, including in Salahuddin where the Mausoleum of Sayid Mohammed bin Ali al-Hadi is located.

Prominent Shi'ite cleric Moqtada al-Sadr ordered his militia, the Peace Brigade, to deploy around the mausoleum, near Balad 93 km (58 miles) north of Baghdad.

Sadr's militia is also deployed in Samarra, a nearby city that houses the shrine of Imam Ali al-Hadi, the father of Sayid Mohammed.

A 2006 bombing destroyed the golden dome of that shrine and set off a wave of sectarian violence.

(Writing by Maher Chmaytelli; Editing by Mark Heinrich)