The former head of the British chemical and biological defence establishment has warned the United States that their decision not to sign an international treaty banning germ warfare will undermine international security.

The damage that this mistrust, as it involves the world's leading power, will cause to international security will be incalculable

Dr Graham Pearson

Graham Pearson said that the United States had based its decision on an "illogical assessment" and that US relations with the international community would suffer as a result.

He was speaking in Geneva at a meeting of the United Nations Biological and Toxin Weapons Convention.

The US refused to sign the proposed treaty last month, saying it would put national security and confidential business information at risk.

The ad hoc group of states party to the 1972 convention is due to complete negotiations on a draft protocol in Geneva on Friday.

Talks continue

When the US ambassador, Donald Mahley, announced last month that the US would not ratify the biological weapons protocol, there was outcry across the world.

However, since the United States' departure from the negotiating table, multilateral talks have continued quietly in Geneva while the implication of the Americans' decision has been assessed by world delegates.

Dr Pearson: The US based its decision on an 'illogical assessment'

Addressing the panel on Wednesday, Dr Pearson, currently with the Department of Peace Studies at the University of Bradford in England, concluded the US had made a "huge and worrying mistake".

He said that "the rejection of the protocol by the United States" will mean "that it will not be trusted by other states" to live up to "its earlier promises and official statements at the highest level".

"The damage that this mistrust, as it involves the world's leading power, will cause to international security will be incalculable," he said.

Dr Pearson urged the rest of the world to press ahead with the treaty in a bid to make the world a safer place.