The statements, issued separately by two groups, have been transmitted to the 15-member U.N. Security Council, which is expected to decide soon whether to authorise a U.S.-led attack on Baghdad.

''(U.S.) President (George W.) Bush has no interest in or understanding of international law,'' said Peter Weiss, vice president of the International Association of Lawyers Against Nuclear Arms (IALANA).

''He is in the process of dismantling the entire structure of law-based international security created since World War II,'' he told IPS.

Weiss said that an attack on Iraq would likely be ''extremely devastating'', based on U.S. Secretary of State Colin Powell's doctrine of ''quick victory through overwhelming force''. ''The use of nuclear weapons cannot be ruled out,'' Weiss said.

Medact, a British affiliate of the group International Physicians for the Prevention of Nuclear War (IPPNW) has estimated that a war on Iraq could cause 48,000 to 261,000 deaths on all sides within the first three months and another 200,000 longer-term deaths, said IPPNW spokesman Victor Sidel, professor of social medicine at New York's Albert Einstein College of Medicine.

''As physicians, many of whom have seen and responded to the consequences of war for both combatants and non-combatants, we consider the price that the Iraqi people are about to pay unacceptable, especially when clear alternatives to war exist and have been advocated throughout the international community,'' he added.

Last month, a team of 10 health experts said that Iraq's 13 million children face greater danger than prior to the 1991 Gulf War. ''Iraqi children are at grave risk of starvation, disease, death and psychological trauma,'' concluded their report.

IALANA, a coalition of more than 200 international lawyers and jurists from over 30 countries, says that, ''there is no precedent in international law for the use of force as a preventive measure when there has been no actual or imminent attack''.

''The Security Council has never authorised force based on a potential, non-imminent threat of violence. All past authorisations have been in response to actual invasion, large-scale violence or humanitarian emergency,'' it added.

The group also said that the Security Council has established mechanisms to address the concerns regarding alleged Iraqi weapons of mass destruction (WMD), including diplomatic pressure, negotiations, sanctions on certain goods with military applications, destruction of stockpiles of WMD, and inspections of facilities able to help produce such weapons.

''Evidence to date is that these mechanisms are not perfect, but are working effectively enough to have led to the destruction and curtailment of most of the Iraqi weapons of mass destruction capability,'' it added.

The United States, which is seeking Security Council authorisation for a military attack on Iraq, is facing opposition by three veto-wielding permanent members of the Council - France, Russia and China. The other Council members with veto powers are the United States and Britain, while the remaining 10 members are rotating, non-permanent and have no veto powers.

An expected U.S. resolution calling for the use of force would need nine positive votes and no vetoes to be adopted. The resolution, which is likely to be tabled after U.N. arms inspectors report on their Iraqi mission to the Council on Friday, could also survive if Russia, China and France abstain, instead of exercising their vetoes.

Bush has warned that he is willing to attack Iraq with or without Security Council authorisation. Last week, a group of 45 experts on international law disputes challenged the president's assertion that the United States does not need Security Council authorisation to attack Iraq.

The writers, all from U.S. universities and non-governmental organisations (NGOs) advocating nuclear disarmament, said the administration's position ''is incorrect and poses a grave danger for the future of international law, the United Nations, and a peaceful international order''.

The administration is basing its argument on its own interpretation of Security Council resolution 1441, which was unanimously adopted late last year and sent inspectors back to Iraq to search for evidence of biological, chemical and nuclear weapons after a four-year hiatus.

''It is clear from that resolution that no individual member state is authorised to use any violation by Iraq, whether very minor and technical or more serious, as legal justification to attack Iraq,'' said University of Pittsburgh law professor Jules Lobel.

The letter said, ''We urge the Bush administration to comply with the U.S. constitution, to comply with the U.N. charter, and not unilaterally attack Iraq.'' .