Iraq's parliament speaker says an investigation is underway into an attack on a Sunni mosque that killed more than 60 people and escalated sectarian tensions.

In a press conference on Saturday, Salim al-Jabouri said a committee of security officials and lawmakers will announce its findings in two days. Al-Jabouri, a Sunni, described Friday's attack northeast of Baghdad as "carnage."

It was not clear whether Shiite militiamen or the Sunni Islamic State extremist group were behind the attack, which prompted two major Sunni blocs, including al-Jabouri's, to suspend talks on forming a new Shiite-led government until the investigation is concluded.

Al-Jabouri didn't comment on the withdrawal, saying he was acting in his capacity as Parliament Speaker and not as a bloc leader.