Korean and American researchers are expected to announce a broad collaboration today under which cloned human embryos will be created in the United States, Britain and South Korea in an effort to develop new ways of studying -- and perhaps curing -- human disease.

Advocates said the collaboration, to be known as the World Stem Cell Hub, will seek to marry Korean expertise in cloning, a field in which that country has become a world leader, with the deep knowledge of U.S. and European researchers in the biology of human diseases. The plan could accelerate some types of medical research that have gotten off to a slow start because of political opposition in the United States, its backers said.

South Korean President Roh Moo Hyun was scheduled to announce the plan Wednesday afternoon at a conference in Seoul. That was the middle of the night, Washington time, and some details were still sketchy as of early last evening. The plan seemed likely to intensify an ethical debate already underway in the United States, though few advocacy groups on either side of the issue were aware of the plan as of late yesterday.

Seven states have passed laws to ban the type of research contemplated under the plan, while six others have gone out of their way to encourage or fund such research. Congress has been sharply divided, though it has passed no law either way. Government policy prohibits the use of federal funds to conduct such work, but it is permitted under current law if carried out with private funds.

The plan would not involve the creation of cloned human beings, which virtually all sides of the debate regard as unethical and unsafe.

Instead, cells would be harvested from patients with diseases that have been hard for researchers to study. Nuclei from such cells would be inserted into human eggs, creating cloned embryos that would begin growing. Instead of implanting such embryos into a woman's uterus, which would be necessary to create a cloned baby, the researchers would destroy them at an early stage to extract cells.

These embryonic stem cells, as they are called, would probably display some characteristics of the disease under study. Scientists would manipulate the cells in the laboratory to seek a better understanding of the genetic defects underlying the illness.

Potentially, the scientists might correct the defects and attempt to reimplant the cells into a patient as a cure or use the cells to discover drugs that could treat the disease.

Under the plan scheduled to be announced today, Korean researchers trained by Hwang Woo Suk of Seoul National University, the first scientist to create cloned human embryos, would perform many technical steps needed to derive the stem cells. Various U.S. and European research institutions would then study the cells, though it is unclear how many will agree to do so.

"Because of politics and funding issues, this expertise has grown up in one particular country more than anywhere else in the world," said Evan Snyder, director of stem-cell research at the Burnham Institute in La Jolla, Calif., who hopes to use cells from the project to study a neurological disease in children. "The Koreans have just become really good at it."

Gerald P. Schatten, a University of Pittsburgh researcher who helped put the new plan together, said the group was seeking $35 million in philanthropic funds to set up the program, which would include cloning laboratories in Seoul, San Francisco and London. The World Stem Cell Hub will operate under strict ethical oversight, he said in an interview last night from Seoul.