Iraqi officials say two senior commanders in Basra were replaced Wednesday, weeks after Iraqi security forces failed in efforts to crack down on Shi'ite militias in the southern city.

Officials say the military chief and police chief were reassigned to Baghdad.

Iraq's security forces launched an offensive in late March against militants loyal to radical cleric Moqtada al-Sadr.  The effort triggered deadly clashes, during which hundreds of security force members refused to fight or gave their weapons to the militants.

In other news, Iraqi Prime Minister Nouri al-Maliki says he is more confident than ever that al-Qaida in Iraq will be defeated.

Mr. Maliki Wednesday spoke to members of the European Parliament during a visit to EU headquarters in Brussels.  He said his government is "determined to defeat terrorism."

U.S. and Iraqi military authorities blamed al-Qaida for a series of fatal bombings in Sunni Arab areas on Tuesday.  More than 50 people were killed and almost 100 were wounded in those attacks in Baquba and Ramadi.

In military operations in Iraq Wednesday, British officials say a coalition airstrike killed four militants and wounded another in Basra.

A British military spokesman said the strike targeted a group carrying rocket-propelled grenades.

And coalition forces say they detained 13 suspected al-Qaida terrorists during operations Tuesday and Wednesday in the Tigris River Valley and northwestern Iraq. 

In another development, the U.S. military says a roadside bomb attack killed two Marines earlier this week in Anbar province.

Some information for this report was provided by AFP, AP and Reuters.