“Three suicide bombers driving tanker trucks sped towards a gathering of security forces at a checkpoint,” an army lieutenant colonel told AFP on condition of anonymity.
He said the attack took place near Sur Shnas, an archaeological site on the banks of the Tigris between the cities of Samarra and Tikrit, the main cities in Salaheddin province north of Baghdad.
“Security forces opened fire, managed to stop two but the third got closer to the group and blew himself up,” the officer said.
Clashes ensued, he said, but “security forces successfully completed preparations to surround Ad-Dawr”, a town just south of Tikrit which is controlled by the Islamic State jihadist group.
A hospital source in Samarra confirmed the toll of 11 dead.
The officer said a large operation would soon begin by army forces and volunteer fighters — known as the Popular Mobilisation units — aimed at retaking Tikrit, one of the jihadists’ main hubs in the country.
Government forces have attempted and failed several times to wrest back Tikrit — the hometown of former president Saddam Hussein — since losing it to IS in June last year.
“We call on the people of Tikrit to leave their city within 48 hours to wrap up the battle of the revenge for Speicher,” said Hadi al-Ameri, commander of the Popular Mobilisation.
His organisation confirmed the truck attack and said it caused casualties but did not say how many.
Speicher is a military base near Tikrit from which hundreds of new, mostly Shiite, recruits were kidnapped before being executed in the early days of the IS nationwide offensive in June 2014.
Shiite militias in particular have always vowed to avenge the Speicher executions, sparking fears of mass killings against Sunnis if Tikrit were to be recaptured.
Ameri heads the Badr organisation, arguably the most powerful Shiite militia in Iraq, and wields direct influence over the interior minister, who is one of his lieutenants.
Five people were also killed further south in Balad Ruz, a town northeast of Baghdad in Diyala province, that Badr helped recapture in January.
Local council member Said Majid said five people were killed and 15 wounded when a car bomb and an improvised explosive device went off in a market area.
IS fighters no longer hold fixed positions in Diyala but can still pose a security threat with such bomb attacks, as they do in the capital Baghdad. (AFP)