A Paris court Thursday rejected an appeal by a French-Vietnamese woman who has been trying to sue Monsanto and other makers of Agent Orange for the chemical's use in the war in Vietnam.

Tran To Nga, who was born in what was then French Indochina, accused 14 agrochemicals firms of causing grievous harm to her and others by selling Agent Orange to the American military, which used the herbicide to devastating effect in Vietnam.

She lost her initial case in 2021, when a French court ruled that the companies enjoyed legal immunity from prosecution because they worked for a sovereign government.

The Paris Court of Appeal used the same argument in rejecting Nga's claim.

Her demands "come up against the companies' immunity status," the court said in its written ruling, seen by AFP.

Nga will now take her case to France's highest appeals court for a final ruling, her lawyers said.

The 82-year-old, who covered the 1955-1975 war as a reporter and has lived in France for the past three decades, also accused the companies of environmental damage.

Campaign groups estimate that four million people in Vietnam, Laos and Cambodia were exposed to the 76 million litres (20 million gallons) of Agent Orange sprayed by US forces to destroy ground cover and food sources in its battle with North Vietnamese troops between 1962 and 1971.

'Long and difficult'

Vietnam blames the chemical for severe birth defects in 150,000 children.

But so far, only military veterans -- from the United States, Australia and Korea -- have won compensation for the after-effects of the highly toxic chemical.

Nga's French lawyers told AFP that she was "disappointed" by Thursday's verdict. "But she is somebody full of wisdom, she knows that this battle is long and difficult."

Vietnam's government called the French court ruling "very regretful". Foreign ministry spokeswoman Pham Thu Hang told reporters that "although the war is over, its effects on the country and the people of Vietnam are still felt".

Companies that made Agent Orange or supplied it to the US army should be made to "take responsibility and address relevant consequences", she said.

Vietnam Dioxine, a French NGO, accused the court of "denying justice to the victims of Agent Orange".

Nga suffers from Type 2 diabetes and an extremely rare insulin allergy, which she linked to exposure to Agent Orange.

She said she also contracted tuberculosis twice and developed cancer, and one of her daughters died of a heart malformation.

Monsanto, which was taken over by German chemicals giant Bayer in 2018, argued the French courts did not have jurisdiction in the case due to the issue of sovereign immunity.