Prosecutors accuse Fernandez of embezzlement through inflated public works contracts with businessman Lazaro Baez during her 2007-2015 presidency.
In a series of statements on Twitter before the trial, Fernandez maintained her innocence and accused her rival President Mauricio Macri of politically motivated attacks.
"A new trial where I should have never been summoned is beginning," she said on Twitter. "This is a new act of persecution with only one goal: to place a former president who opposes the current government on the defendant's bench during a presidential campaign."
"Clearly it's not about justice," she added. "Just about creating a new smoke screen that aims to distract Argentines and Argentina — increasingly less successfully — from the dramatic situation our country and our people live."
Pile of corruption probesFernandez faces multiple other corruption investigations into her administration and that of her late husband, President Nestor Kirchner, but this case is the first one to reach court.
The trial is scheduled to be extended for a year and approximately 160 witnesses will testify, with hearings held weekly.
If she is found guilty, she could be sentenced to up to 10 years in prison. However, as a current senator she has immunity from arrest.
Macri enters election with economy in tattersThe trial comes after Fernandez on Saturday said she would run for vice president alongside her former cabinet chief Alberto Fernandez. She had previously been expected to run for president.
A populist, Fernandez is a divisive politician yet popular among the poor. She had been viewed as a top challenger to the center-right Macri.
Macri's chances of reelection have come under threat due to a waning economy, high inflation, a weak currency and rising unemployment.
cw/jm (AFP, AP, dpa, Reuters)
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