US President George W. Bush (L) and British Prime Minister Tony Blair walk together from their meeting at the US Embassy in Brussels in this February 22, 2005 file photo. [Photo/Agencies]

The then UK Prime Minister Tony Blair took Britain to war against Iraq in 2003 on the basis of flawed intelligence and failure to share the many personal notes he sent to President George W Bush with his ministers, according to a massive report on Britain's role in the Iraq war published on Wednesday, seven years after it was commissioned.

The report, according to analysts, was damning in its criticisms.

"There is evidence of gross recklessness," said Philippe Sands, a leading UK human rights lawyer.

The seven volume report, 2.6 million words long and three times as big as the complete works of William Shakespeare and five times as large as Leo Tolstoy's epic novel War and Peace, was ordered by Blair's successor as Prime Minister, Gordon Brown in 2009.

As the report was unveiled at a conference center in Central London, several hundred demonstrators from the "Stop the War" movement, which held regular protests before and during the invasion, held a silent vigil in the street, many carrying the movement's signature placards which showed a deliberate misspelling of Blair name, "BLIAR."

Blair, who was Labour Party prime minister from 1997 to 2008, took Britain to war in Iraq as part of a US-led coalition, ostensibly because Iraqi leader Saddam Hussein had weapons of mass destruction. In the 2003 invasion and aftermath which toppled Saddam, 179 British soldiers were killed.

From 2003 to 2014, when US combat units were withdrawn, 4,491 US service personnel were killed.

In the event, no evidence of weapons of mass destruction, a euphemism for chemical or nuclear weapons, was found.

Blair has repeatedly been accused by UK politicians from all parties of being too close to the then US President Bush. The inquiry found that Blair sent 31 private notes to Bush, often without reference to his ministers or senior officials.

Before the various options for dealing with Saddam had been exhausted, Blair wrote to Bush that he was "with you, whatever," Chilcot said.

The report has been delayed because of a rule that anyone mentioned in the report had a right of reply to any criticism, and the protracted process of obtaining Blair's communications with Bush. The US has refused to allow Bush's responses to Blair's communications to be released.

The report, headed by civil servant Sir John Chilcot, found that there had been serious intelligence failures, and a string of bad judgments made by senior officials.

Chilcot said his investigations and interviews with over 150 witnesses had concluded that there was a lack of planning for what would happen after the invasion, and "the consequences of invasion were over-estimated."

"The weapons of mass destruction case was presented with unjustified certainty," Chilcot said in his presentation, adding that because Blair and Bush had not waited for a second UN Security Council resolution, "the UK was undermining the UN Security Council's authority."

"We have concluded that the decisions taken on legal justification were not satisfactory,"he added.

Blair reacted to the report by saying his decision to invade along with US-led forces was "taken in good faith and in what I believed to be the best interests of the country."

The former prime minister also said he would take full responsibility for any mistakes.

Prime Minister David Cameron told the House of Commons today "Clearly, we need to learn the lessons of this report."

Opposition leader Jeremy Corbyn, who in the past has called for Blair to stand trial for war crimes, said the invasion had been on "false pretexts, and has long been regarded as illegal. The war fuelled and spread terrorism in the region."

Blair, who has since built up an international consulting firm with many government contacts, including China and Saudi Arabia, said he did not believe the removal of Saddam Hussein "is the cause of terrorism we see today."

But he added in a statement after the report was released: "I will take full responsibility for any mistakes."

An estimated 150,000 Iraqis, mainly civilians, were killed in the invasion and its aftermath, and over one million made homeless.

Contact the reporter on chris@mail.chinadailyuk.com