Former SNP depute leader Jim Sillars has called on Holyrood to "take the necessary legislative steps" to allow Tony Blair to be tried for war crimes for his role in the conflict in Iraq.

The veteran nationalist said a retrospective Iraq War Crimes Act should be passed by the Scottish Parliament, as it would be an "outrage" if the former Labour prime minister is permitted to "walk away free" after a conflict which claimed the lives of 179 UK service personnel.

READ MORE: Tony Blair has 'got his comeuppance today': Mum of Scots soldier killed in Iraq is pleased with Chilcot report

Mr Sillars, a former SNP MP, made the plea as Sir John Chilcot published his lengthy and long-awaited report into the conflict - finding that the UK "chose to join the invasion of Iraq before the peaceful options for disarmament had been exhausted".

The report said "military action at that time was not a last resort", as it also concluded statements about the risk posed by Iraq's weapons of mass destruction were "presented with a certainty that was not justified".

Scottish First Minister Nicola Sturgeon tweeted that the report was "damning", adding: "War not last resort, based on flawed, unchallenged intel and unsatisfactory legal decisions."

READ MORE: Chilcot report: Tony Blair takes responsibility for Iraq 'mistakes' but made in 'good faith'

Sir John's report revealed that eight months before the UK Parliament approved military action in Iraq, Mr Blair had committed himself in writing to backing then US president George Bush over Iraq, telling him: ''I will be with you whatever.''

Ms Sturgeon said that comment "suggests pre-determination and lack of proper decision making".

She added that the "lack of preparation for aftermath and failure to properly equip/support troops for scale of challenge also appalling".

Her predecessor Alex Salmond said: "It is now clear from the report that military action was not the last resort as Blair stood in Parliament on March 18 2003 to ask MPs to support his case for war."

READ MORE: Chilcot report: Tony Blair rushed ill-prepared troops to war with no imminent threat

Mr Salmond, now the SNP's foreign affairs spokesman at Westminster, added: "In the days, weeks and months ahead, the intimate detail of this report will only implicate further a former prime minister who recklessly committed the country to war without collective judgement, and personally failed to ensure there was a plan for delivering a future for the people of Iraq.

"After such carnage, people will ask inevitable questions of was conflict inevitable and worthwhile? The answer from Chilcot is undoubtedly no. And who is responsible? The answer is undoubtedly Tony Blair. There must now be a consideration of what political or legal consequences are appropriate for those responsible."

Mr Sillars said action at Holyrood to allow Mr Blair to be put on trial is the "logical point" of conclusion for the parties which had opposed the Iraq conflict, including the SNP, Liberal Democrats and the Greens, who between them have 74 of the 129 MSPs in the Scottish Parliament.

He served as depute leader of the SNP for a period from September 1991 to September 2002, part of Mr Salmond's first spell as SNP leader.

Mr Sillars argued that Mr Blair could not be "held to account" at the International Criminal Court in the Hague, so an alternative means of prosecution would be for an Iraq War Crimes Act, bringing aggression into domestic law, to be enacted either by Westminster or Holyrood.

READ MORE: Alex Salmond: Chilcot shows Blair recklessly committed UK to war

In a letter to the Herald newspaper, he said it is "unlikely" Westminster would act "given the number of 'guilty by association' MPs on the green benches".

He stated: "That leaves the Scottish Parliament where there is a majority among the parties that vehemently denounced the Iraq war as illegal - SNP, Greens and Liberal Democrats.

"With the potential majority they exercise, now is the time for all three parties to take their opposition to its logical point, and bring forward the necessary legislative steps to have Mr Blair indicted in Scotland."

Rose Gentle, whose son Gordon died while serving in Iraq with the Royal Highland Fusiliers, said the report meant Mr Blair ''got his comeuppance today''.

Fusilier Gentle, from the Pollok area of Glasgow, was 19 when an IED exploded under his Land Rover in Basra in June 2004.

Speaking after the report was published, Mrs Gentle said she was pleased with its findings.

''I didn't think we were going to get that verdict today but I'm really pleased,'' she said.

''I hope he (Blair) goes to his bed and thinks 'What the hell have I done?' because he will never be forgiven.

''He will be remembered not as a prime minister but as a person who sent them on an illegal war.

''I would love to see him in court.''

Asked what she would say to the former Labour leader, Mrs Gentle said: "Why did you kill my son, send my son to be killed? Because I hold him responsible for the murder of my son."

Speaking about the report, she added: "What we've been hearing and what we've been reading has been really hard and I think that's why there's a lot of mothers and fathers that's been in tears today.

"A lot of us have held it back for weeks and what's been confirmed today has really gut-wrenched a lot of us."

In total, 19 Scottish servicemen died during the Iraq campaign following the invasion.

The mother of Lance Corporal Allan Douglas, 22, who was shot in January 2006, said the hole her son had left "will never be filled".

Diane Douglas, from Aberdeen, told the Evening Express newspaper: "We didn't get proper closure.

"I think about him every day and think of things I want to say to him every day.

"That hole will never be filled. I want to see justice done for the lives that were lost."

She added: "I want him (Tony Blair) to admit that it was illegal for a start and to admit that he did wrong.

"I would hope to see something come out of it, I would like parents to get compensation."

Speaking on his LBC radio show, Mr Salmond said he believes parliamentary action could be taken against Mr Blair.

He said: "I still think some form of cross-party parliamentary action and accountability is required. I'm open minded about what it should be.

"There have been talks between MPs across the parties. We wanted to see the report first, we'll be meeting over the next few days.

"It's going to take people time to assimilate all the information in the report but I favour such action, I favour a means of parliamentary accountability because I don't believe that these things can just be sorted out by saying we will improve the intelligence gathering, we'll restore cabinet government, we'll have a sequence of decision making.

"At the end of the day these were decisions made by a human being and that prime minister was Tony Blair."

Responding to a caller who asked whether the parliament could prevent Mr Blair from holding international positions such as that of Middle East peace envoy, Mr Salmond added: "I'd like to see the ICC (International Criminal Court) investigate a crime of aggression but I don't think that's going to happen.

"I'd genuinely like to see a prosecution for that offence in this country but I'm not certain that's going to happen.

"But I think parliamentary action is possible and although it might seem a little thing, you've given the example of would it be possible to stop somebody holding public office again. The answer to that question is yes, yes it would. The parliament can actually do that."

He continued: "I'm not confident about domestic criminal action against Tony Blair.

"I'm not ruling it out and there's going to be a meeting on Friday incidentally of people with expertise in these matters to examine every possible iota, but parliamentary action is possible and the parliamentary action against Blair is not a matter of a vendetta or using this report to see him off.

"It's a matter of principle that unless there is a direct line of personal accountability then you cannot say with any certainty that disasters like Iraq won't happen again."