By Khalid al-Ansary

BAGHDAD, July 29 (Reuters) - Iraqi forces began a major security operation in northeastern Diyala province on Tuesday, officials said, in the latest crackdown on Sunni Arab insurgents and Shi'ite militias.

Sunni Islamist al Qaeda has sought to stoke tensions in religiously and ethnically mixed Diyala, where a series of bomb attacks have killed scores of people.

Suicide bombers killed 27 people in the provincial capital Baquba, 65 km (40 miles) northeast of Baghdad, this month alone.

"The operations started today with raids in Baquba," Defence Ministry spokesman Major-General Mohammad al-Askari said on Iraqiya state television.

Al Qaeda is orineting its activities more towards northern Iraq after being forced from former strongholds in Baghdad and Iraq's west.

Details of troop numbers involved in the operation were not immediately available. The U.S. military has said the crackdown would be run by Iraqi forces with minimal U.S. involvement.

Large numbers of U.S. troops took part in a big crackdown in Diyala last year, but insurgents have proved resilient. Women in particular have carried out numerous suicide attacks in Diyala.

Al Qaeda has increasingly used female suicide bombers because they are less likely to be as thoroughly searched.

"The aim is to completely cleanse Diyala province. The Iraqi army will be executing this operation," said Major-General Abdul-Kareem al-Rubaie, commander of Diyala security operations.

Similar offensives elsewhere in Iraq, including in Basra city in Iraq's south and Baghdad's Sadr City slum -- both once strongholds of Shi'ite cleric Moqtada al-Sadr's Mehdi army -- have been largely successful.

The U.S. military commander in Iraq, General David Petraeus, told Reuters on Monday that Iraq's security forces might be able to take on security responsibility for the whole country by the end of 2009.

Iraqi forces have responsibility for security in 10 of the 18 provinces.

However, the U.S. military has repeatedly said recent security gains are fragile and reversible.

On Monday, suicide bombers killed nearly 60 people in Baghdad and the northern city of Kirkuk. (Additional reporting by Waleed Ibrahim, Writing by Mohammed Abbas; Editing by Richard Balmforth)

AlertNet news is provided by