WASHINGTON - Sharp differences over providing poor countries with access to inexpensive drugs for AIDS and other diseases promise to cloud this week's World Trade Organization summit. A drug-patent compromise is a top priority for trade ministers from the U.S., Canada, Mexico, Europe, China, India, Japan and a host of developing countries when they meet in Sydney, Australia.

The session will also hit on hot-button topics such as agricultural subsidies in rich countries. The trade ministers called the "mini-ministerial," beginning Thursday night and running through Friday, to try to iron out several issues that threaten to hold up the current round of WTO talks. Despite optimistic talk from drug-producing countries such as the U.S., skepticism runs high that the 144 countries of the WTO can reach a compromise next month on the drug-access issue, which has dogged the WTO for years. Failure to cut a deal this year will slow progress on the overall trade talks, which are supposed to wrap up by 2005.

Trade ministers agreed last year that poorer countries facing serious health threats should be allowed to avoid international drug patents by buying generic copies from manufacturers in other countries. The agreement was critical to launching the latest round of global trade talks, but ministers left the details to be hammered out by the end of 2002.

Both the EU and the U.S., the world's two major drug producers, have offered drug-patent proposals that are far more restrictive than those favored by developing countries and many nongovernmental organizations. The EU and U.S. plans would limit patent-busting production to drugs needed to fight epidemics such as AIDS and malaria, and then only for the poorer developing countries.

There also would be strict limits on which countries could produce the generics. Developing countries want access to a wider range of drugs, while a large coalition of NGOs is pushing to allow any poorer country to contract for delivery of patented medicines from whomever it chooses. "This is nowhere near close to a breakthrough. Those who think it is are guilty of wishful thinking," said Ellen 't Hoen, who leads the drug-access campaign for the Paris-based Médecins Sans Frontières. Success at the summit, a U.S. trade official said, will depend "on whether people want to find a practical solution or one that would undermine the WTO's agreement on intellectual-property rights."

The official criticized NGOs for "trying to break patent protections on every conceivable health product, even X-ray machines." Protesters in Sydney hope to turn the event into another high-profile condemnation of what they see as the dominance of multinational companies over the poor in the developing world.

Police have erected two miles of fencing around the venue for the talks at Sydney's Olympic Park and have banned all downtown protest marches Thursday. U.S. pharmaceutical companies have fought hard to keep a WTO generic-drug agreement as limited as possible, fearing a wave of patent infringements that could result in prescription drugs washing back into Europe or North America from developing countries. Phillip Day in Sydney contributed to this article.