The failure to plan for post-war Iraq ended with a 'humiliating' secret deal with Iraqi insurgents who had been killing British troops, the Chilcot report found.

Sir John insisted no hindsight was required to foresee the difficulties that would be encountered in Iraq after the invasion.

The risks of external strife, regional instability and the threat of Al Qaeda were 'explicitly identified' before the war, he said.

But the planning and preparations for Iraq after the fall of Saddam Hussein were 'wholly inadequate'.

Ill-equipped: A British soldier escapes from a burning armoured vehicle in September 2005 after angry crowds hit it with petrol bombs in Basra

'The scale of the UK effort in post-conflict Iraq never matched the scale of the challenge', Sir John said.

The most consistent strategic objective was apparently to reduce troop numbers – even as the security situation deteriorated.

Attention was turned to Afghanistan, where Britain was fighting another war.

Military chiefs failed to recognise the need for more soldiers, refused to acknowledge equipment shortfalls and ignored advice on a growing insurgency in central Iraq, the report found.

It said General Lord Michael Walker, Chief of the Defence Staff from 2003 to 2006, repeatedly failed to revise troop numbers during the campaign. Despite the failing security situation in south-east Iraq in spring 2004, he was 'explicit' that no additional soldiers were required.

Air Chief Marshal Graham Stirrup – head of the RAF from 2003 to 2006, then head of the Armed Forces until 2010 – advised there should be no change to plans to reduce troop numbers, saying there were 'compelling reasons' why the UK should 'press on' with handing over security to Iraq while building up forces in Afghanistan.

The inquiry also concluded that senior officers should have ensured soldiers were aware of the Rules of Engagement and knew how to deal with lawlessness.

Military chiefs failed to recognise the need for more soldiers, refused to acknowledge equipment shortfalls and ignored advice on a growing insurgency in central Iraq, the report found

The planning and preparations for Iraq after the fall of Saddam Hussein were 'wholly inadequate'

Admiral Lord Michael Boyce, Chief of the Defence Staff between 2001 and 2003, failed to set out plans on how troops would be able to establish a safe and secure environment if lawlessness broke out, the report found. He also advised Tony Blair that the military plan would work.

Faced with widespread looting after the invasion, and without instructions, UK commanders had to make their own judgments.

Brigadier Graham Binns, commanding 7 Armoured Brigade which had taken Basra City, told the inquiry he had concluded that 'the best way to stop looting was just to get to a point where there was nothing left to loot'.

By the summer of 2007, Basra Palace – centre of UK operations in southern Iraq – was the 'most heavily mortared and rocketed place' in the country.

In August that year, the Government – which was then led by Gordon Brown – concluded that troops had no choice but to withdraw to the relative safety of the air base outside the city.

Risks has been identified

The Chilcot report disclosed that, behind the scenes, British officials had to negotiate with Iraqi militias to allow troops safe passage to withdraw from the base.

Ministers agreed to the release of detainees suspected of involvement in the killing of British personnel, in return for a reduction in attacks.

This was despite the 'scepticism' of many in both the British and US military, with one US colonel saying Shia militia leaders 'outlasted the British will to continue the fight'.

Sir John said: 'By 2007, militia dominance in Basra – which UK military commanders were unable to challenge – led to the UK exchanging detainee releases for an end to the targeting of its forces.

'It was humiliating that the UK reached the position in which an agreement with a militia group which had been actively targeting UK forces was considered the best option available.'

He added: 'The UK military role in Iraq ended a very long way from success. It is an account of an intervention which went badly wrong, with consequences to this day.'

Despite explicit warnings, the consequences of the invasion were underestimated, the report found. Sir John said Mr Blair had been warned that military action would increase the threat from Al Qaeda to the UK. He was also told an invasion might lead to Iraq's weapons and capabilities being transferred into the hands of terrorists.

The report said General Lord Michael Walker, Chief of the Defence Staff from 2003 to 2006, repeatedly failed to revise troop numbers during the campaign

Mr Blair did not ensure there was a flexible, realistic and fully resourced plan that integrated the military and civilians, as well as addressing the risks, the report found. Sir John said: 'The failures in the planning and preparations continued to have an effect after the invasion.'

More than 200 Britons were killed as a result of the conflict in Iraq, and by July 2009, at least 150,000 Iraqis had died.

Summing up the situation in Iraq today, Bashar Maki, whose brother was killed in 2003 as British troops went in, said: 'Up until today we pay for this wrong decision. Thanks to this policy, we have sectarian divisions, bombings, displacement, a lack of security and safety, and a long list of damages.'

Consequences to this day

Speaking from Iraq, Saad Al Shamary, an ex-officer in the army, told the Mail: 'Blair and Bush lied to us. They came for their own interests, they destroyed our country and killed every beautiful thing. They founded extremism and jihadists we had never heard about.

'It is too late for the report, they should have discovered this mistake at the beginning, not after 13 years of destruction and violence.'

The Government also failed to take account of the magnitude of the task of stabilising and reconstructing the country.

The security situation in Baghdad and south-east Iraq began to deteriorate soon after the invasion.

From 2006, the UK military was conducting two campaigns in Iraq and Afghanistan without the 'sufficient resources to do so'.

Decisions on resources were affected by the demands of the operation in Afghanistan, with equipment being shipped to the latter at the expense of troops on the ground in Basra.

l.brown@dailymail.co.uk

Faced with widespread looting, and without instructions, UK Commanders had to make their own judgments

Poor kit 'should not have been tolerated'

Soldiers were desperately ill-equipped in battle because of the headlong rush to war and inadequate response to problems in Iraq, said Sir John.

Defence chiefs were too slow to react to the threat of roadside bombs, and delays in replacing vulnerable Snatch Land Rovers 'should not have been tolerated'.

Confirming the fears of grieving families, the report found the Ministry of Defence planned the invasion in a hurry, leaving soldiers with the Land Rovers known as 'mobile coffins' and a lack of basic kit.

The inquiry chief said the military failed to identify those risks with ministers – and equipment could have saved British soldiers' lives.

Instead of concentrating on Iraq, the MoD began to focus on Afghanistan. But it had 'insufficient resources' to do so, which meant helicopters and spying assets were taken away from soldiers in Basra.

The risks of running parallel operations from 2006 had not been properly thought through, Sir John found. The 'serious shortfalls' in kit, protection against chemical and biological attacks, and ammunition had grave consequences for soldiers.

The report cited the death of Sergeant Steven Roberts, who was killed in March 2003 after a lack of protective vests prompted him to lend his to a colleague.

'It was judged that his death could have been prevented if he had still had his body armour', it said.