United States veterans of the Vietnam war say they are pushing for legislation in Washington to fund research this year into the effects of wartime use of chemical defoliants in Vietnam.

The vice-president of their organisation, Vietnam Veterans of America, Thomas Corey, said in Hanoi that the money -- a million and a half dollars -- should be used to fund scientists from both countries for studies in Vietnam.

Chemical defoliants, used to spray vast areas of jungle cover during the war, have been blamed for tens of thousands of birth defects in Vietnam.

Nearly three million American soldiers and tens of thousands of Australians, New Zealanders and South Koreans were also exposed to the toxin.

Official figures have estimated that two million people in Vietnam are suffering from the after-effects of exposure.