Iraqi forces backed by US troops launched a major assault on Tuesday against insurgents in the northeastern province of Diyala, one of the last bastions of Al-Qaeda and one of the most dangerous places in the country.
"The operation began in Diyala early this morning and we have begun raids in some neighbourhoods of the city of Baquba," said Ragib al-Omeiri, chief of the operations bureau in Baquba.
"Iraqi police and Iraqi army are working together with the US army," he told AFP.
The operations were planned and executed by Iraqi forces, with US troops taking on a secondary role, US army spokesman Major John Hall said in an email to AFP.
"The goal of the operation is to seek out and destroy criminal elements and terrorist threats in Diyala and eliminate smuggling corridors in the surrounding area."
Interior ministry spokesman Major General Abdul Karim Khalaf had announced on July 13 that the Iraqi military would launch an assault on Diyala, considered one of the most dangerous places in Iraq.
Earlier this month the US military said a force of 30,000 Iraqi soldiers and police were amassing in Diyala and its capital Baquba, an area where insurgents regularly carry out attacks.
Aided by the US military and Iraqi forces, local anti-Qaeda groups known as "Sahwa" or Awakening councils, have inflicted severe blows on the militants but they continue to wage attacks in the region.
Several recent strikes have been carried out by female suicide bombers, with one woman killing eight people when she blew herself up as an Awakening patrol passed by in Baquba last week.
Awakening groups began in the western province of Anbar when Sunni tribal leaders turned on their former Al-Qaeda allies in 2006, and since then similar bodies have sprung up across Iraq, supported and paid for by the US military.
On July 7, another female bomber killed two people and wounded 14 others after blowing herself up at a bustling street market in Baquba, while June another women killed 16 near in Baquba, near the office of the Diyala.
Defence ministry spokesman Mohammed al-Asskri told AFP that the security operations codenamed "Glad Tidings" would specifically target Qaeda operatives and other outlaws.
Colonel Ali al-Karkhi, commanding officer of Iraqi forces in Khan Beni Saad, a town near Baquba, said in an interview with AFP last week that "Diyala remains the most dangerous province in Iraq."
"It is a mini-Iraq. There are Sunnis, Shiites, Kurds, Christians."
The US military also believes that many militants in the area are "rogue" members of the Shiite Mahdi Army militia, the militant wing of radical cleric Moqtada al-Sadr's movement.
Diyala, fed by the Euphrates and Diyala rivers, was once the granary of Iraq and the country's orange capital with its lush orchards.