Sunni insurgent groups that were previously allied with Al-Qaeda in Iraq have turned against it, killing its leaders, attacking its supporters and vowing to drive it out of the country.

At least two Al-Qaeda commanders have been killed by Iraqi insurgents in Baghdad. Others have been forced to flee after insurgents passed their details to US and Iraqi commanders. Fierce fighting has broken out between insurgent groups and Al-Qaeda in Anbar province, west of Baghdad.

Until the death of Abu Musab al-Zarqawi, the leader of Al-Qaeda in Iraq, in a US airstrike last summer, the groups cooperated with it in their bloody struggle with the coalition forces. But the insurgents have come to believe that Al-Qaeda in Iraq is destabilising the country by the indiscriminate slaughter of civilians, often with truck bombs.

Some senior Sunni insurgents believe that Al-Qaeda in Iraq shares the agenda of Iranian-backed Shi’ite militias to plunge the country into ever more violent sectarian conflict rather than concentrating on the fight against the US-led coalition.

Late last year Salam al-Zubaie, Iraq’s deputy prime minister, began secret talks with the Sunni groups with the aim of coaxing them away from Al-Qaeda. He held meetings with commanders of groups including the 20th Revolutionary Brigade, the general command of the Iraqi armed forces, the Islamic Army of Iraq, the Ba’ath party and the Salah al-Deen al-Ayyubi Brigade.

He encouraged them to form a unified Sunni alliance that could fight Al-Qaeda and attack Iranian influence. They proved receptive to his arguments.

“Both Al-Qaeda and Iran seem to have an identical agenda to try to widen the sectarian split between Sunnis and Shi’ites, maintaining instability,” Abu Baker, a commander in the 20th Revolutionary Brigade, told The Sunday Times last week. “They stepped up their attacks on innocent Iraqi people and we could not accept that.”

A senior commander in the Islamic Army said Zubaie had promised not only to help to unify the Sunni groups but also to provide them with financial and logistical support to stop Iranian infiltration.

The insurgents demanded assurances from the government that they would not be arrested or attacked by the security forces. They also asked for promises that they could eventually join the security forces.

There was one sticking point. “We insisted that our fight with the occupying forces would continue as they are to blame for our current situation,” the Islamic Army commander claimed.

“Zubaie’s response was that first we had to get rid of Al-Qaeda and turn ourselves into a strong legal force to be reckoned with. Then we’d be in a position to negotiate with the occupying forces and demand their withdrawal. This was something we could not accept.”

Within weeks, however, the insurgent groups set out to “cleanse” parts of Baghdad of Al-Qaeda influence. Shaker Zuwaini, an Al-Qaeda emir, was assassinated by the 20th Revolutionary Brigade in the Adel district of Baghdad. The emir of the Amiriya district was also killed and another commander was chased away from the Khadra district.

Abu Omar, leader of a Ba’ath insurgent group and military commander in Amouriya, said: “Al-Qaeda have turned into a bunch of criminals and gangsters up to their eyes in kidnapping and robberies. We resolved to put an end to them.”

The drive against Al-Qaeda has continued despite an attempt to assassinate Zubaie last month. He was seriously injured by a suicide bomb. Al-Qaeda claimed responsibility.

Zalmay Khalilzad, the outgoing US ambassador, said the United States had also held talks with Sunni insurgents “to explore ways to collaborate in fighting the terrorists”.

Al-Qaeda in Iraq, which has carried out many of the most brutal attacks on civilians, is made up largely of foreign fighters. Although it shares a name with Osama Bin Laden’s group, it is unclear how closely the two are linked.

General David Petraeus, the US commander, blamed Al-Qaeda for provoking carnage in Tal Afar, in northwestern Iraq, with a truck bomb that killed 152. Shi’ite militants and police then cold-bloodedly executed as many as 70 Sunnis.

- The Hollywood star Alec Baldwin was so moved by the story of a soldier’s last day with her family before training to serve in Iraq that he will help to pay for her university education after she leaves the forces. He tracked down the mother of Resha Kane, 18, in New Mexico to offer his help.

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