A federal judge in Washington yesterday temporarily blocked the Obama administration’s efforts to expand stem cell research, ruling in a case brought by a former MIT scientist and others who oppose embryonic stem cell research.

Royce C. Lamberth, chief judge of the US District Court for the District of Columbia, said in his 15-page decision that regulations designed to expand federal funding for embryonic stem cell research violated a law prohibiting destruction of embryos for research purposes.

Additionally, the judge ruled that former MIT researcher Dr. James L. Sherley and other scientists who study less controversial adult stem cells would face “actual, imminent injury’’ because of the competition for federal dollars that would be stoked by expansion of research into embryonic stem cells.

The immediate implications of the preliminary injunction were unclear last night, said Kevin Casey, Harvard University’s associate vice president for governmental relations. Harvard has been a recipient of federal grants under the new regulations, and it was uncertain whether the judge’s decision would affect funds already awarded to scientists or only future funding, he said.

The university, Casey said, was “disappointed at this preliminary halting of this research, as it will slow progress that so many who suffer afflictions are relying on.’’ But, he added, the university remained optimistic that the courts will ultimately validate the use of federal money for expanded embryonic stem cell research.

Dr. Leonard Zon, director of the stem cell program at Children’s Hospital Boston, called yesterday’s ruling a “step backward.’’

“It throws things into a confused state,’’ he said.

The hospital receives federal funding for embryonic stem cell research. It also gets philanthropic grants that can be used for research not supported by the government.

Sherley did not respond to calls for comment, but one of his attorneys said he would not be commenting because of the ongoing litigation.

Sherley, now a senior scientist with Boston Biomedical Research Institute, made headlines in 2007 when he held a 12-day hunger strike protesting MIT’s decision to deny him tenure and accusing administrators of racism. Sherley, who is black and a proponent of controversial theories about stem cells, said at the time that he had not been given the freedom to challenge scientific orthodoxy that white professors are given.

“This is the case of an uppity Negro, and there is a group of faculty who would like to see me move on,’’ Sherley, the only black professor among what was then 40 members of the biological engineering department, said at the time.

Sherley and his research team at Boston Biomedical are studying adult stem cells that are involved in cancer initiation and contribute to aging, according to the lawsuit.

The other scientist who remains party to the lawsuit is Theresa Deisher of AVM Biotechnology, with headquarters in Seattle. The original suit included other plaintiffs, but the court had earlier found that they did not have legal standing to proceed.

One of the original plaintiffs, Nightlight Christian Adoptions, which supports the adoption of embryos for implantation, had maintained that the research would reduce the availability of embryos.

Lamberth declared that it is in the public interest to stop use of the expanded guidelines because they would lead to the destruction of embryos.

Steven H. Aden — senior counsel for the Alliance Defense Fund, a nonprofit legal alliance of Christian attorneys and co-counsel in the suit — said yesterday that the alliance was encouraged by the “common sense’’ ruling.

“We believe that the court’s interpretation is consistent with Congress’s intent in keeping taxpayer money out of research that destroys human life,’’ Aden said.

In March 2009, President Obama revised limits on stem cell research imposed eight years earlier by the Bush administration. Those restrictions declared that scientists could use federal money only to work with existing embryonic cells lines.

Human embryonic stem cells have the capacity to develop into any tissue in the body, such as insulin-producing cells that might eventually treat diabetes or neurons that could replace those that perish as Lou Gehrig’s disease progresses.

But such research has provoked dissent from activists such as Sherley, who argue that it is immoral for scientists to work with cells derived from embryos because they have to be destroyed to extract stem cells.

The Obama administration attempted to walk a scientific and moral tightrope in its regulations, which allow scientists to work only with stem cells derived from donated embryos. The donors must give their explicit permission for scientific use of the embryos, typically stored at in vitro fertilization clinics.

Even then, federal dollars cannot be used in the process of harvesting the cells; federal funds are limited to studying the cells after they have been extracted.

Lamberth ruled, in essence, that is a distinction without merit under a 1996 law known as the Dickey-Wicker Amendment.

“Had Congress intended to limit the Dickey-Wicker to only those discrete acts that result in the destruction of an embryo, like the derivation of [embryonic stem cells], or to research on the embryo itself, Congress would have written the statute that way,’’ the judge concluded. “Congress, however, has not written the statute that way, and this court is bound to apply the law as it is written.’’

The irony, said George Annas, a medical ethics specialist at the Boston University School of Public Health, is that researchers generally believed that even the Obama administration’s interpretation of the statute was too narrow because it did not allow federal dollars to be spent creating embryos to study specific diseases.

Zon and his colleague, Dr. George Q. Daley, lamented that the ruling will force them once again to rely on philanthropy to underwrite their research.

“Our lab will have to return to the old mode of keeping human embryonic stem cell research separate from everything else, which means slower progress,’’ Daley said. “It’s a shame.’’

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