The intelligence was provided by an informant who had "family disputes" with one of the victims, the Iraqi Supreme Judicial Council said in a statement reported by the state-owned Iraq News Agency.

The informant, "nine officers and three agents" are being investigated over the incident that took place on Thursday in Al-Rashayed village in the central Iraqi province of Babylon.

An investigating judge heard the statements of the 13 men, the news agency added.

On Thursday, rapid intervention units and intelligence forces stormed a house in Al-Rashayed to pursue "two individuals accused of terrorism".

The state news agency said later that 20 members of the same family were killed and that the owner of the property "opened fire" and "refused to surrender".

"The questioning revealed that the cause of the tragedy was false intelligence provided by the nephew and son-in-law of one of the victims, because of family disputes," the judicial council's statement said.

The informant gave "false information to the security services indicating the presence of two wanted terrorists in the victims' house", it said.

Investigations are ongoing and four arrest warrants have been issued, the statement said.

On Friday, Interior Minister Othman al-Ghanemi travelled to Al-Rashayed where he sacked the Babylon police chief and announced the formation of a commission to investigate "the unit that carried out the operation".

Security forces said on Friday that a "number of officers and individuals" had been called in for questioning, without providing details on their identities.