Tuesday's conference will bring together veterans and delegates from at least six countries.

Vietnamese civilians and soldiers from all sides of the conflict have claimed health defects from exposure to Agent Orange.

Victims from Vietnam and elsewhere have been fighting for compensation from Monsanto Corp, Dow Chemical and other former producers of the toxic chemical.

The US government has officially rejected responsibility for the health defects of Agent Orange victims.

A New York court last year dismissed a Vietnamese lawsuit representing millions of victims. The Vietnamese team has launched an appeal.

In January this year, a South Korean court ordered Dow Chemical and Monsanto to pay $65 million in compensation to 6800 Vietnam war veterans.

"To fight and defeat the Americans in the war was difficult. Winning in court is even more difficult"

Professor Nguyen Trong Nhan,
vice-president of the Agent Orange Victims Association

Michael Marine, the US ambassador to Vietnam, said this month that Washington and Hanoi had held some "co-operative exchanges" but he criticised Vietnam for blaming too many cases of disability on the toxin.

"I hear this constant refrain, the term 'victims of Agent Orange', and what they're describing is every person who's disabled. And that's, as I'm sure you know, simply inaccurate."

Code named Operation Hades, Agent Orange was part of a defoliant programme to deny cover for the North Vietnamese soldiers or Viet Cong.

The chemical stripped away jungle cover and destroyed food crops.

Dioxin, the main ingredient of Agent Orange, has been blamed for hormonal and genetic changes that cause diseases such as leukaemia, immune deficiencies, reproductive and developmental changes and nervous system damage.

It accumulates in animal and human tissue and can be passed on to babies through breast milk.

Tough fight 

Professor Nguyen Trong Nhan, vice-president of the Vietnam Dioxin/Agent Orange Victims Association, said: "To fight and defeat the Americans in the war was difficult. Winning in court is even more difficult.

"Even if we have sufficient evidence about our victims, the American judges can always reject it."

Nhan says that between 1961 and 1971, the US military dropped more than 100,000 tonnes of toxic chemicals on southern Vietnam, exposing anywhere between 2.1 million and 4.8 million people.

Poisoning the environment

Joan Anne Duffy Newberry, a US Air Force nurse in Vietnam during the war, said: "It's bad when you're not just killing the enemy soldier but you're also killing his grandchildren and you're poisoning his environment."

"It's bad when you're not just killing the enemy soldier but you're also killing his grandchildren"

Joan Anne Duffy Newberry,
US Air Force nurse during the Vietnam war

US veterans who claimed health disorders caused by Agent Orange won a victory in 1984 when US chemical companies paid $180 million into a veterans' fund without admitting any liability.

Duffy Newberry, said: "I've been working in the United States for 25 years on this issue and this is the first time I've felt such hope, especially to hear that the Koreans got a judgement against the chemical companies."

Agent Orange was one of several defoliants used. The others were Agent Pink, Agent Blue and Agent White. The names were derived from the colour coding of the drums containing the defoliants.