The Obama administration on Monday pleaded with a U.S. appeals court to allow federal funding of human embryonic stem cell research to continue, arguing a ban would ruin numerous projects and cost millions of dollars.

A federal judge last month blocked such funding, saying it violated U.S. law because it involved the destruction of human embryos and put other researchers working with adult stem cells at a competitive disadvantage for federal grants.

The Obama administration appealed and faced tough questions from a three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit about what real harms would occur and how the government separates research from the destruction of the embryos.

Judge Thomas Griffith, appointed by President George W. Bush in 2005, questioned irreparable harm and whether the money was just going to be used elsewhere for other research in the interim until the embryonic stem cell projects could be resumed if the government succeeded in its appeal.

Judge Brett Kavanaugh, also a Bush appointee, repeatedly questioned the Obama administration lawyer about how the government separated funding from the destruction of the embryos from the use of the embryos for research.

Deputy Assistant Attorney General Beth Brinkmann said the injunction against the funding was a setback for the field and that biological material would be destroyed at a cost of tens of millions of dollars.

She said the embryos used were going to be destroyed regardless and not solely for the purpose of research.

The Obama administration asked that the injunction be lifted pending its appeal of the lower court ruling.

The appeals court made no ruling from the bench after the hearing, which lasted more than 90 minutes despite having been allotted only 30 minutes to the case. A decision is expected soon.

The injunction on the funding came after a challenge by two researchers who work with adult stem cells and opposed embryonic stem cell work -- Dr. James Sherley, a biological engineer at Boston Biomedical Research Institute, and Theresa Deisher, of Washington-based AVM Biotechnology.

Brinkmann said there was no harm to either doctor because Deisher only recently applied for federal funding and Sherley had already received some $425,000 in federal grants.

But the lawyer for the doctors, Thomas Hungar, said the federal law was clear in banning the research funding for embryos that had been destroyed and that it's all speculation by the Obama administration that the projects would suffer.

However, Judge Judith Rogers, appointed by President Bill Clinton, said that money spent on projects that were halted and ruined represented a loss to the taxpayers.

California George W. Bush