UN says Soviet use of toxins can't be proven

A United Nations report based on inquiries made by a team of experts in Afghanistan, Laos, and Kampuchea on the alleged Soviet and Vietnamese use of toxic chemical weapons in those areas concludes that such accusations ''can not be proven.'' But, according to Monitor correspondent Louis Wiznitzer, the report does cite ''circumstantial evidence'' of chemical warfare.

A similar report issued last year stated the UN could not reach a final conclusion on the matter. This year's report was stronger, adding that the experts ''could not disregard the circumstantial evidence suggestive of the possible use of some sort of toxic chemical substances in some instances.'' The US government recently accused Moscow of waging chemical warfare, which the Soviet Union categorically denied.