Hospital officials speaking to Aljazeera said a blast on Tuesday had killed 14 people and wounded at least eight.
Black smoke rose into the sky and ambulances raced to the scene where a car bomb went off targeting an Iraqi army convoy as the driver attempted to enter al-Muthanna airport.
A police source said the blast was caused by a car bomb that detonated next to a truck carrying recruits to the base, housed in a disused airport.
Other officials said they were still investigating the cause of the explosion.
A US army spokesman was quoted as saying that it was a bomber on foot who detonated explosives as the vehicle approached. He was not able to confirm the casualty toll.
Hospital officials said all the victims appeared to be young men.
Fighters have frequently targeted Iraqis queuing up to join the police and army.
Also on Tuesday, armed men ambushed the convoy of an Iraqi politician in western Baghdad, killing two of his sons, police said.
"Yes, my two sons died and my bodyguard as well. It was a gunfire attack on my car near my house in Baghdad"
They said Mithal al-Alusi, secretary-general of the Democratic Party of the Iraqi Nation, had survived the attack.
Two of his sons were killed, al-Alusi said.
"Yes, my two sons died and my bodyguard as well. It was a gunfire attack on my car near my house in Baghdad," said the 52-year-old politician.
His sons were aged 22 and 30, one of them a father of three. The bodyguard was a father of four, al-Alusi said.
Al-Alusi was waiting for his car when the armed men opened fire on the vehicle. "I was the target of the attack, there is no doubt."
Ties with Israel
"There are people who every day in the name of Islam or of the Baath party, kill those who want a free Iraq," he said.
Al-Alusi was Ahmad Chalabi's
adviser before being expelled
Al-Alusi had been an adviser for Shia politician Ahmad Chalabi. He caused a stir when he voiced his support for a normalisation of ties with Israel.
After he became the first Iraqi politician to visit the Jewish state, al-Alusi and Democratic Party of the Iraqi Nation were expelled from Chalabi's political Iraqi National Congress.
Al-Alusi is a controversial figure in Iraq: he has been a vocal critic of Syria and Iran, and was widely criticised in Iraq for visiting Israel last year.
For anti-US fighters, roadside
bombs are a favoured weapon
In separate incidents, two Iraqis were killed and seven wounded in bomb blasts north of Baghdad, security sources said on Tuesday.
A civilian died and six others were wounded, including three women, when a roadside bomb hit their vehicle in Shurgat, 300km north of the capital on Monday, police Lieutenant-Colonel Faris Mahdi said.
All casualties were reportedly from the same family.
In the third attack, one soldier was killed and another wounded when their patrol was targeted by a roadside bomb late on Monday in Dhuluiya, 70km north of Baghdad, army Lieutenant Husain Abbas said.
Also on Tuesday, a US military base east of al-Qaim town near the Iraqi-Syrian border came under fierce mortar attack on Tuesday morning, Aljazeera has learned.
The targeted site was one of the three US military bases in the area.