Baghdad - Iraqi police have confirmed that a man they detained last week is the mysterious "emir" of an umbrella group including al-Qaeda in Iraq, an Iraqi security spokesman said Tuesday.

Baghdad security spokesman Qassim Atta told the al-Arabiya satellite news channel that investigations had confirmed that the man Iraqi police arrested in Baghdad last Thursday was Abu Omar al-Baghdadi, the shadowy leader of the self-proclaimed Islamic State in Iraq.

In March and May 2007, respectively, Iraqi police said that al-Baghdadi had been arrested and killed.

After those reports turned out to be false, US Brigadier-General Kevin Bergner in July 2007 told reporters that the US military believed al-Baghdadi was a myth created "to put an Iraqi face on the leadership of al-Qaeda in Iraq."

Tuesday's "confirmation" followed news that Iraqi police had arrested three suspected members of al-Qaeda in Iraq in al-Ramadi, 100 kilometres west of Baghdad.

Police in al-Ramadi, the capital of the heavily Sunni al-Anbar province, told the German Press Agency dpa that police had raided a suspected al-Qaeda hideout on the northern outskirts of the city shortly before dawn and arrested three people.

"The raid followed intelligence that this group had worked with al-Qaeda to attack Iraqi police and soldiers," police said.

Tuesday's arrests followed a string of recent bloody attacks targeting Shiite Muslims in the capital.

On Thursday, even as Iraqi authorities first said they had arrested al-Baghdadi, suicide bombers killed 87 people and wounded 125 more in two attacks targeting Shiite Muslims in Baghdad and the province of Diyala.

Thursday's attacks followed six car bombs in predominantly Shiite neighborhoods of Baghdad that left at least 36 people dead.

The spike in violence, particularly in the capital, has raised fears that the relative calm that had recently returned to the country may be at an end.

It also comes amid signs of a brewing confrontation between Sunni "Sahwa," or "Awakening" councils, Sunni militias enticed to fight insurgents, and the Iraqi government, which is now dominated by Shiites and Kurds.

Militiamen in Abu Ghraib, west of Baghdad, left their posts on Thursday, following their leader's resignation after four of his bodyguards, including his son and nephew, were arrested.

In late March, the US military passed control of the Awakening Councils to the government of Iraq.

In the weeks running up to the transfer, Iraqi security forces began arresting members of the Awakening Councils, charging that they were insurgents and supporters of the former ruling Baath party.

Clashes broke out in the Baghdad slum of Fadhil when Iraqi security forces arrested Adil al-Mashhadani, the head of the local Awakening Council.

It took Iraqi soldiers, backed by US troops, two days to quell the uprising that followed. At least 15 people were killed in the fighting, and security forces acknowledged that hundreds may have escaped with their weapons.