The four police officers were killed and two others wounded when a roadside bomb blew up near their convoy in Samarra, north of Baghdad.
Fighters have been waging a bloody campaign against the country's security forces, killing more than 35 people in attacks over the past two days.
Aljazeera learned that Abd al-Husain Khazaal al-Basri, a correspondent with US-funded pan-Arab television station Al-Hurra, was killed by unknown attackers in the southern city of Basra on Wednesday.
Al-Basri, who was also the head of the information department in the Basra governorate, was shot dead near his house in al-Maaqal district.
Al-Basri's four year-old son was also killed and his driver wounded.
The victim, in his 40s, was also a member of the Shia political party, Dawa.
Al-Hurra reporter Abd al-Husain
al-Basri was killed on Wednesday
In other violence, Col Riad Gatia Allawi was captured in Dora district in southern Baghdad, officials said. He is the interim Oil Ministry's representative to the interim Interior Ministry.
Aljazeera also reported that Shaikh Ali al-Jiburi, head of the office of the Association of Muslim Scholars (AMS) in al-Karkh district in Baghdad, was arrested by US and Iraqi soldiers who raided his house at dawn on Wednesday.
No further information on the arrest was available.
The US army said its troops killed a fighter near Balad, north of the capital, as he was planting a bomb on Tuesday.
A US soldier has been killed in the northern Iraqi city of Mosul, the US military said on Wednesday.
There were also reports that a gas pipeline linking Iraq's northern oil hub of Kirkuk to the Baiji refinery had been damaged by a rocket attack.
Oil infrastructure attacks have
cost the government $8 billion
"A rocket hit the gas pipeline near al-Fatha, 90km southwest of Kirkuk," an unnamed official at the North Oil Company said on Wednesday.
"The attackers used rockets because the pipeline is located in an area sealed off with barbed wire and well protected," he said, adding he hoped the blaze would be put out by the end of the day.
According to the interim Iraqi government, attacks on oil infrastructure have cost the country $7 billion-$8 billion in exports since the March 2003 US-led invasion.