The United Nations said it is hopeful that a new strategy to strengthen a global treaty on germ warfare will work. The United Nations says U.S. involvement is a key to success.

Arms experts from 146 countries have gathered in Geneva to consider a new plan to strengthen enforcement of the Biological Weapons Convention.

The proposal involves setting up concrete measures to secure pathogens and toxic substances. It would also criminalize their use. Other provisions would forbid using infectious diseases as weapons and establish a code of conduct for scientists.

Although the Bush administration has been instrumental in putting forward a number of the issues to be discussed, it is not clear whether it will push for discussions on the treaty to continue until the next review in 2006.

The U.N. point man for disarmament, Jayantha Dhanapala, said American participation is crucial. "What is important is that the United States remains engaged in the discussion that is going on right now," he said.

The United States withdrew its support from the treaty last year, after more than six years of negotiations. It said inspections would not be able to detect violations, and could possibly give away defense secrets to potential enemies.

Some developing countries have their own reservations about the treaty, and say too much emphasis has been placed on compliance, rather than cooperation.

But Ambassador Tibor Toth, who chairs the U.N. negotiations, said he is hopeful a consensus can be reached. "There is an increasing snowballing support from all the different constituencies in the conference. The U.S. attitude is a cautious one. I think my feeling is it would be quite difficult for the U.S. not to agree to this proposal," he said.

The United Nations and a number of groups monitoring developments in biological weapons say the negotiations are made more urgent by rapid advances in biotechnology. A new watchdog organization, called the Bio-Weapons Prevention Project, has been launched in Geneva to keep the discussions going if the U.N. process fails.