Researchers from Harvard University will clone human embryos for the purposes of developing stem cell lines, the Harvard provost, Steven Hyman, announced yesterday. The contentious cloning program, spearheaded by a co-director of the Harvard Stem Cell Institute, Douglas Melton, will be the first of its kind in America.

The Harvard development will increase the number of stem cells available for American research. At present, American scientists working in stem cell research have a limited number of stem cell lines to work with because the federal government has prohibited such work to be funded with federal money.

The announcement came just a day after Ian Wilmut, the man who cloned the first mammal, Dolly the sheep, reversed his previous opposition to human embryonic cloning. In his book, “After Dolly,” Mr. Wilmut, an Edinburgh University professor, writes that synthesizing an embryo of 100 cells is not the same as cloning a person.

If Mr. Melton and his colleagues are successful, they will increase the supply of stem cells dramatically by synthesizing embryos in a petri dish and deriving new stem cell lines from them several days after they die. The embryos will be derived by combining egg cells provided by female donors with the genetic material of adult cells.

The president of Harvard, Lawrence Summers, called the development “a seminal event in the university’s effort to advance this tremendously promising area of science and fulfill that promise as quickly as possible for the countless patients suffering from diabetes, Parkinson’s disease, heart disease, cancers, and a host of other illnesses.

“While we understand and respect the sincerely held beliefs of those who oppose this research, we are equally sincere in our belief that the life-and-death medical needs of countless suffering children and adults justifies moving forward with this research,” he said.

Mr. Melton will work with an assistant professor at Harvard, Kevin Eggan, and a physician scientist at the institute and Children’s Hospital Boston, George Daley. Dr. Daley said at a press conference yesterday that he has already started conducting experiments.

But Dr. Hyman said none of the researchers, including Dr. Daley, will speak publicly about their results until they have been peer-reviewed and prepared for publication.

“The research is very much in its infancy,” Dr. Daley said, “and clinical applications may be a decade or even more in the future. But based on the work that we’ve done in mouse models, we do believe very strongly there is a significant opportunity here.”

Prior to being approved, the institute’s proposal underwent two years of ethical and scientific scrutiny from numerous Harvard committees, including the Institutional Review Board of the Faculty of Arts and Science.

The decision comes just over a year after the House Appropriations Committee voted against an amendment to restrict embryonic stem cell research.

Rep. David Weldon, a Republican of Florida who introduced the bill to the Appropriations Committee last year, expressed dismay at the Harvard news.

“I am outraged but not surprised,” he said through a spokesman. “It’s now clear that embryo stem cell researchers fully intend to exploit women for the express purpose of using their eggs to create and destroy human embryos solely for experimental research. Unfortunately, this will be the way things go unless Congress finally decides to act.”

According to Harvard’s press release, donors will not be paid, only reimbursed for travel and other expenses “directly related to the research.”

Mr. Weldon’s bill, which fell to a vote of 36-29 in June 2005, proposed that the National Institutes of Health require institutions both in the public and private sector to stay out of the human cloning business in order to be eligible for state funding. A similar bill may come to the Senate before the end of the year, according to Mr. Weldon’s office.

The Senate also may soon vote to expand federal funding for research on stem cells derived from human embryos. The House passed a bill to ease restrictions on funding last year, but President Bush vowed to veto it if it came before him.