Updated 12.40

Footage has emerged that appears to show an Islamic State in Iraq and Syria (ISIS) fighter questioning and killing Iraqi soldiers.

It comes after the insurgents, who have seized large parts of Iraq in the past week, released graphic pictures claiming to show some of the 1,700 Shia soldiers they had shot dead near Tikrit.

According to a translation of the first clip, militants order their prisoners to chant the ISIS slogan "Baqiya", which is thought to mean "(ISIS) will remain in existence" or "Islamic state will stay".

When asked where the government forces are, a soldiers replies they have left.

The fighters then threaten to chop off one of the soldiers' heads.

WARNING: Some viewers may find these images of intimidating behaviour upsetting

The earlier images posted online showed the Sunni insurgents loading captives on to flatbed trucks, forcing them to lie face-down in a ditch with their arms tied behind their backs before they were shot dead.

Chief Iraqi military spokesman, Lieutenant General Qassim al Moussawi, confirmed the authenticity of the pictures and said he was aware of cases of mass murder of captured soldiers. However, the images have not been independently verified.

Jen Psaki, spokeswoman for the US State Department, said: "The claim by ISIS that it has massacred 1,700 Iraqi Shia air force recruits in Tikrit is horrifying and a true depiction of the bloodlust that these terrorists represent.

UN Secretary General Ban Ki-moon said the reports were "deeply disturbing" and called for justice.

Prime Minister Nouri al Maliki has vowed to recapture territory seized by the insurgents last week.

But in the latest fighting, residents of the northern town of Tal Afar, near the Syrian border, said ISIS had taken control after a dawn raid.

Iraqi security forces have claimed to have killed 279 "terrorists" in the last 24 hours.

Mr Maliki said: "We will march and liberate every inch they defaced, from the country's northernmost point to the southernmost point."

US evacuate

The US has said it will evacuate some embassy staff from Baghdad after three explosions in the capital left at least 15 people dead and dozens injured.

The US is reportedly preparing to stage direct talks with Iran, set to begin next week, though the White ...

The White House, while declining to comment on the report, did not deny it.

Aircraft carrier the USS George HW Bush has arrived in the Persian Gulf as President Barack Obama considers possible military action against ISIS.

The US has "airlift assets" ready to evacuate people if they are requested, the Pentagon confirmed.

ISIS insurgents have been attacking the city of Tal Afar in northern Iraq, using rockets seized from military arms depots.

Martin Chulov is reporting for the Guardian from the region, he gave Newstalk's Breakfast the latest: 

Meanwhile, former British Prime Minister Tony Blair has denied claims the invasion of Iraq over which he presided could be responsible for current instability, instead blaming the West's more recent failure to act on conflict in Syria: