BAGHDAD - Iraqi officials worked Saturday to calm soaring tensions after the killing of 70 people at a Sunni mosque, as Washington branded the beheading of an American journalist a "terrorist attack." In the latest violence, a suicide bomber detonated an explosives-rigged vehicle at the interior ministry's intelligence headquarters in Baghdad, killing two people, officials said.
The attack at the mosque in Diyala province on Friday, which most accounts said was the work of Shiite militiamen, threatens to increase anger among Iraq's Sunni Muslim minority with the Shiite-led government at a time when an anti-militant drive depends on their cooperation.
The violence came as the US, which is carrying out air strikes in Iraq against Islamic State (IS) jihadists, ramped up its rhetoric over the grisly killing of journalist James Foley, carried out by the group and shown in a video posted online.
Deputy National Security Advisor Ben Rhodes said the beheading of Foley "represents a terrorist attack against our country".
And in an unanimous statement Friday, the UN Security Council condemned the murder as "heinous and cowardly".
Call for unity
On Saturday, Iraq's Sunni parliament speaker sought to calm sectarian tensions stirred by the bloody attack on the Sunni mosque.
Salim al-Juburi called for political unity and said "the main aim (of the attack) is to foil all the efforts that have been made to form a government." "All the political entities condemned the crime, all of them expressed their anger about what happened," he said in televised remarks.
"Now we are waiting for practical measures to hold the criminals accountable." Iraqi premier-designate Haidar al-Abadi, a Shiite, has condemned the attack and called for "citizens to close ranks to deny the opportunity to the enemies of Iraq who are trying to provoke strife."
Rights group Amnesty International termed the attack a "massacre" and said Iraqi authorities "must properly investigate the unlawful killing of dozens of worshippers."
Army and police officers said the attack on the Musab bin Omair Mosque in Diyala came after Shiite militiamen were killed in clashes, while other sources said it followed a roadside bomb near one of their patrols.
Doctors and the officers put the toll from the attack, in which worshippers were sprayed with machine-gun fire, at 70 dead and 20 wounded.
Two officers had earlier blamed IS for the attack, saying it had included a suicide bombing, a hallmark of the group, but most accounts pointed to Shiite militiamen.
The interior ministry announced it is investigating the attack, which it said was carried out by two men on a motorbike following a bombing targeting security and volunteer forces in the area.
The government turned to militiamen to bolster its flagging forces during the IS offensive, sparking a resurgence of groups involved in brutal sectarian killings in past years.
Ibrahim Aziz Ali, whose 25-year-old nephew was among those killed, told AFP he and other residents heard gunfire and rushed to the mosque, where they were fired on by snipers.
Five vehicles with images of Imam Hussein, one of the most revered figures in Shiite Islam, were parked at the mosque, Ali said.
When they could finally enter, "we found a massacre," he said.
US Vice President Joe Biden, writing in The Washington Post, said Washington would back a system of "functioning federalism" in Iraq as a means to breach the divisions in the country.
The United States was prepared to "further enhance" its support for Iraq's fight against IS, he said.
Since launching an air campaign against IS in Iraq on April 8, the US has carried out more than 90 strikes, including three on Friday against militants around the Mosul dam, the country's largest.
Pentagon chiefs have said that anti-IS operations in Syria may also be needed.
"They marry ideology and a sophistication of strategic and tactical military prowess," US Defence Secretary Chuck Hagel. "This is beyond anything we have seen."
Foley's killing has stoked Western fears that territory seized by the militants in Syria and Iraq could become a launchpad for a new round of global terror attacks.
Foley, a 40-year-old freelance journalist, was kidnapped in northern Syria in November 2012.
In the execution video, released online, a black-clad militant said Foley was killed to avenge US air strikes against IS.
The man, speaking with a clear south London accent, paraded a second US reporter, Steven Sotloff, in front of the camera and said he too would die if Washington kept up its attacks.