Prime Minister Tony Blair has been accused of creating the conditions for terror to thrive in Iraq.
Winnie Ewing claimed Mr Blair had lied about Iraq
The attack came as the Scottish National Party (SNP) conference wound up in Inverness with a fierce attack on Westminster and Mr Blair.
Both party leader Alex Salmond and president Winnie Ewing called for him to take responsibility over the war.
Delegates also backed plans to undercut UK business taxes to stimulate the economy after gaining independence.
In her keynote speech, Mrs Ewing called for Scotland to play a greater role in the new expanded Europe and accused Mr Blair of lying over the war in Iraq.
She said: "The House of Commons may be described as an archaic institution.
"But when a prime minister lies to the country, lies to the nation and lies to the Commons, then the archaic remedy of impeachment is appropriate."
Earlier, Mr Salmond had continued his campaign against the prime minister.
He said: "What the prime minister and President Bush are responsible for is creating the circumstances in which terrorism, disarray, a near-civil war and a bloodbath are occurring in Iraq at the present moment.
"They bear the responsibility for creating the circumstances in which terrorism is flourishing, but individuals who commit atrocities are responsible for the atrocities they commit."
But he stopped short of holding the prime minister directly responsible for the plight of British civil engineer Kenneth Bigley, saying: "Individuals who commit atrocities are responsible for the atrocities they commit."
Mrs Ewing also told delegates that Scotland had not benefited as it should have done from Europe because of Westminster incompetence, citing the loss of Objective One status for the Highlands.
The conference has been the most united in years
She finished her address with the plea: "Stop the world, Scotland wants to get on."
Meanwhile, Roseanna Cunningham, the former party deputy leader, has failed to secure a place on the SNP's national executive council.
The business resolution to undercut taxes, tabled by enterprise spokesman Jim Mather, called for moves to improve "overall fiscal competition".
Delegates voted in favour of setting targets for business rates, water rates, corporation tax and employers' national insurance contributions to be reduced below UK levels after independence.
Mr Mather said: "Our case has bounced our opponents into making economic performance our top
priority and confronts them daily with the twin realities of their powerlessness and Scotland's urgent need to compete."
The resolution also outlined tax breaks to stimulate creative industries and renewable energy.
But critics of the move argued the commitment went too far in tying the hands of a future SNP government.
In other debates on the final day of the Inverness conference, members voted in favour of a statutory definition for rape.
It follows concern that recent court judgements will make it almost impossible to secure convictions.
A review of the law on sexual offences is being carried out by the Scottish Law Commission.
Debates were also taking place on fisheries, local government and the controversial M74 motorway extension in Glasgow.