A federal judge on Monday blocked the Obama administration from funding human embryonic stem cell research, ruling that the support violates a federal law barring the use of taxpayer money for experiments that destroy human embryos.

U.S. District Judge Royce C. Lamberth issued a preliminary injunction that prohibits the National Institutes of Health from funding the research under the administration's new guidelines, citing an appeals court's ruling that the researchers who had challenged the less-restrictive policy have the legal standing to pursue their lawsuit.

The decision, a setback for one of the administration's most high-profile scientific policies, was praised by opponents of the research.

"We are encouraged that the court has recognized the seriousness of the ethics and the funding of embryonic stem cell research," said David Prentice, senior fellow for life sciences at the Family Research Council.

The ruling stunned scientists and other advocates of the research, which has been hailed as one of the most important advances in medicine in decades because of its potential to cure many diseases but has been embroiled in controversy because the cells are obtained by destroying days-old embryos.

"This is devastating, absolutely devastating," said Amy Comstock Rick, immediate past president of the Coalition for the Advancement of Medical Research, a group of patient organizations that has been lobbying for more federal funding.

"We were really looking forward to research finally moving forward with the full backing of the NIH. We were really looking forward to the next chapter when human embryonic stem cells could really be explored for their full potential. This really sets us back," Rick said. "Every day we lose is another day lost for patients waiting for cures."

Tracy Schmaler, a Justice Department spokeswoman, did not discuss how the administration intends to respond to the ruling, saying only that "we're reviewing the decision." The NIH had no immediate comment.

Steven Aden, a lawyer with the Alliance Defense Fund who filed the suit, said the court will need to clarify whether the injunction affects work using money already issued to researchers under the administration's new guidelines or blocks additional funding.

In his 15-page decision, Lamberth cited "unambiguous" legislation by Congress in 1996, called the Dickey-Wicker Amendment, which prohibits federal funding for "research in which a human embryo or embryos are destroyed, discarded, or knowingly subjected to risk of injury or death greater than that allowed for research on fetuses in utero."

In 1999, Harriet S. Rabb, a lawyer for the Department of Health and Human Services, concluded that the NIH's support of embryonic stem cell research did not violate the amendment if the funds were used only for experiments involving the cells -- not to procure them. The cells themselves are not embryos, she said.

Said Sean Tipton of the American Society for Reproductive Medicine: "NIH carefully designed polices to allow federally funded scientists to explore the potential of human embryonic stem cell research without violating Dickey-Wicker. The NIH policies on stem cell research make it clear that federal funds can be used to investigate cells and tissues created from human embryonic stem cells, but not to create them."