Image caption Scientists say stem cell research could help find cures for diseases including Alzheimer's

A US appeals court has overturned an earlier order to suspend federal funding of stem cell research.

The Washington court said opponents of the research, who say it is illegal because it involves the destruction of human embryos, were unlikely to succeed in their lawsuit to stop the funding.

The ruling marks a significant victory for US President Barack Obama, correspondents say.

President Obama lifted a ban on funding for stem cell research in March 2009.

Soon after, US District Judge Royce Lamberth issued a temporary injunction on the move while a legal challenge went ahead - although this suspension was itself overruled on appeal, pending a final decision.

The US Court of Appeals in Washington ruled 2-1 on Friday that a 1996 US law against federal funding of embryo destruction was "ambiguous", and "did not prohibit funding a research project in which an ESC (embryonic stem cell) will be used".

'Momentous day'

Scientists say the research could lead to breakthroughs for treatments of spinal cord injuries and diseases including Alzheimer's and Parkinson's.

Opponents, who include religious groups, argue that the research is unethical and illegal.

The suit opposing federal funding, which was also backed by some Christian groups, was brought against the National Institutes of Health (NIH).

The NIH and the White House both welcomed Friday's ruling.

"This is a momentous day - not only for science, but for the hopes of thousands of patients and their families who are relying on NIH-funded scientists to pursue life-saving discoveries and therapies that could come from stem cell research," NIH Director Francis Collins said in a statement.

White House spokesman Nick Papas said the decision was a victory for scientists and patients.

"Responsible stem cell research has the potential to treat some of our most devastating diseases and conditions and offers hope to families across the country and around the world," he said.