San Francisco ? Just a few years ago, Michigan State University scientist Jose Cibelli was considered the leading expert on cloning human embryos to treat and study disease.

Now, there’s no debate that the cloning king is Hwang Woo-suk of Seoul National University.

On Thursday, Hwang announced yet again that he had successfully cloned human embryos, this time extracting stem cells from embryos created using the DNA of sick and injured patients. It was the second time in a little more than a year that Hwang had successfully cloned.

Hwang is succeeding where the United States is failing because generous South Korean government support helped him create an efficient cloning factory. In his lab, an army of researchers trained in specialized individual tasks mans a high-tech assembly line that often operates 24 hours a day, Cibelli and others say.

In contrast, the few U.S. researchers eager to clone are left scrambling for funds and staff and must contend with legal vagaries as well as staunch opposition from President Bush, who reaffirmed his position on Friday with a veto threat.

“I’m very concerned about cloning,” Bush said. “I worry about a world in which cloning becomes accepted.”

No U.S. scientist is known to be actively cloning, though several have plans to start soon.

“We don’t have this issue as a priority. We have Iraq and the economy and the price of gas and people aren’t thinking of cures for diseases,” said Cibelli, a co-author on the scientific paper Hwang published last year disclosing his first cloning success. “The Koreans have the complete support of their government.”

Overseas advances

Cibelli was the lead scientist at Worcester, Mass.-based Advanced Cell Technology when that company announced in 2001 it had cloned human embryos. But that experiment was widely seen outside the company as a failure because Cibelli and colleagues could only coax the cells to divide a few times before they died.

On Thursday, British researchers said they had cloned a human embryo and that their research has been submitted for publication.

The goal of so-called therapeutic cloning of human embryos is not to create babies but to extract stem cells, which are created in the earliest days after conception and give rise to the human body. Scientists hope to use the cells as replacement parts for diseased and injured organs.

Legitimate cloning researchers vow never to create a baby. They say their work will help them better understand diseases by watching them progress from the earliest moments. And Hwang himself said Friday that it will be years – maybe decades – before his team’s breakthroughs can benefit humans.

In South Korea, where a stamp was issued commemorating Hwang’s achievements, cloning research is supported at the highest level of government. Not so in the United States, where Bush vowed Friday to veto proposed legislation that would lift severe funding restrictions he placed on stem cell research in 2001.

American attempts

Stem cells are extracted from days-old embryos, which are destroyed in the process. Bush and such religious conservative groups as the Roman Catholic Church believe life begins at conception and are offended by the research.

And although the administration does not prohibit the private or state funding of cloning projects, U.S. researchers say a lack of federal support is hampering their efforts.

Both legislative houses in Massachusetts have passed measures allowing human therapeutic cloning. And although Republican Gov. Mitt Romney promised Thursday to veto the bill, its supporters appear to have the votes to override him.

In California, researchers are hopeful that a new $3 billion stem cell research institute will jump-start the moribund U.S. cloning field. The voter-approved law that created the California Institute of Regenerative Medicine in November allows for the funding of human cloning for research.