Gunmen killed four policemen and three soldiers in Iraq on Saturday, the latest attacks in a surge in violence that authorities have failed to curb despite wide-ranging operations against militants.

Gunmen killed four policemen and three soldiers in Iraq on Saturday, the latest attacks in a surge in violence that authorities have failed to curb despite wide-ranging operations against militants.

Prime Minister Nuri al-Maliki has nevertheless vowed to press on with the campaign in a bid to combat Iraq's worst violence since 2008, and on Saturday the interior ministry announced the killing of a senior Al-Qaeda-linked militant.

In Saturday's deadliest attack, gunmen killed four police, who were buying ice near Tikrit, north of Baghdad.

Security forces often purchase large blocks of ice to distribute to nearby checkpoints in order to cope with Iraq's sweltering summer heat.

Also north of the capital, gunmen killed three soldiers in an attack on a patrol in the restive Muqdadiyah area of Diyala province.

In the far south, a magnetic "sticky bomb" attached to a truck went off in the parking lot of the port of Umm Qasr, a local official said.

No group immediately claimed responsibility for the attacks, but militants linked to Al-Qaeda frequently carry out attacks against security forces.

Attacks have killed more than 3,480 people since the beginning of 2013, according to figures compiled by AFP.

Security forces have been carrying out wide-ranging operations in multiple provinces including Baghdad, after brazen July assaults on two prisons, claimed by an Al-Qaeda front group.

Maliki has said more than 800 militants have been arrested and dozens killed in the operations.

Interior ministry spokesman Brigadier General Saad Maan said on Saturday that security forces had killed a top Al-Qaeda militant in Tikrit and detained two of his aides, but did not identify the man killed.