U.S. President Barack Obama has lifted limits on federal funding of embryonic stem cell research, and Canadian scientists are wondering how the move will affect their own funding and work.

The announcement, which he had promised throughout his presidential campaign, overturns a policy set in 2001 by former president George W. Bush that limited taxpayer money for embryonic stem cell research to 60 stem cell lines that had already been created.

Only 21 of those lines have proven useful to researchers and scientists have complained that their work has been hampered by the funding restrictions.

Obama acknowledged Monday he recognizes the divisiveness of the issue of using embryos for research.

"Many thoughtful and decent people are conflicted about or strongly oppose this research. I understand their concerns and I believe we must respect their point of view," Obama said ahead of signing an executive order lifting the funding ban.

"But after much discussion, debate and reflection, the proper course has become clear. The majority of Americans from across the political perspective and from all backgrounds and beliefs have come to the consensus that we must pursue this research, that the potential is great and with proper guidelines and strict oversight, perils can be avoided."

The president promised that the changes would not open the door to human cloning, which he called "dangerous, profoundly wrong, and has no place in our society -- or any society."

He insisted the funding ban reversal was needed to stop the U.S. from falling behind the rest of the world in this promising area of research.

"When government fails to make these investments, opportunities are missed. Promising avenues go unexplored. Some of our best scientists leave for other countries that will sponsor their work. And those countries may surge ahead of ours in the advances that transform our lives," Obama said.

Canadian researchers seemed divided over the announcement, because it could mean more money finding its way to U.S. scientists, and Canadians heading south for more opportunities.

"Basically we both now, the United States and Canada, at this moment both have the same -- very similar -- policies and permissions. The difference is the U.S. has the means. And I think that that speaks volumes," Mick Bhatia, scientific director of the Stem Cell Biology Research Institute at McMaster University in Hamilton, told The Canadian Press.

However, Bhatia and others said the involvement of U.S. researchers would mean greater progress in the field.

"Science is not defined by countries. And having the U.S. scientists not be players to the degree that they normally would be has been problematic," Michael Rudnicki, scientific director of the Canadian Stem Cell Network, told The Canadian Press from Prague.

"They've struggled under the Bush administration, no question. And I'm quite happy for U.S. science -- and international science for that matter."

Government money

The changes will not allow scientists to use federal funds to create embryos for research. That has been banned since 1996, when the Dickey-Wicker amendment was passed. Instead, it will permit scientists who want to work with many more, newer stem cell lines that have been created since 2001 to apply for government money for the research, instead of relying on private donations.

Obama's executive order gives the National Institutes of Health four months to come up with new guidelines about when it is ethical and legal to pay for embryonic stem cell research.

He has no power to overturn the Dickey-Wicker ban, says Melody C. Barnes, his chief domestic policy adviser. The president believes stem cell research "should be done in compliance with federal law," she said.

On signing the order, Obama opened the door to research that many argue could lead to treatments or cures for a vast array of disorders, such as muscular dystrophy and Parkinson's disease.

Former first lady Nancy Reagan and late actor Christopher Reeve had both lobbied to end the restrictions on stem cell research.

On Monday, Obama honoured Reeve for his tireless efforts to raise awareness about the issue. He also pointed out that it is still unclear how much federal money will be spent on stem cell initiatives. Figures will only be known when scientists apply for, and receive, grants.

"Medical miracles do not happen simply by accident," Obama said.

Researchers who have been eager to access funding for further research into stem cells are cheering the news.

"We've got eight years of science to make up for," said Dr. Curt Civin, whose research allowed scientists to isolate stem cells and who now serves as the founding director of the University of Maryland Center for Stem Cell Biology and Regenerative Medicine.

"Now the silly restrictions are lifted."

Critics denounce decision

But some political and religious leaders, as well as anti-abortion activists, are deploring the move, arguing that using embryos for research crosses a moral line because a potential human life is destroyed. They argue that scientists should focus on using adult stem cells that come from human tissue.

"For several years, significant progress has been achieved with adult stem cells derived from non-embryonic sources, including umbilical cord blood, brain, amniotic fluid, skin and even fat cells," Republican Congressman Chris Smith of New Jersey, co-chair of the House Pro-life Caucus, said Monday. "Patients with diseases including leukemia, type 1 diabetes, multiple sclerosis, lupus, sickle cell anemia and dozens of other maladies have significantly benefited from adult stem cell transfers."

However, many genetic researchers counter that embryonic stem cells are the most flexible and thus most promising form of stem cell. Others note that the embryos used for research are typically leftovers from fertility clinics that would have been thrown away anyway.

But some, such as Sen. Sam Brownback, a Republican from Kansas, say no research at all should be conducted on embryos if it means the embryos' destruction.

"If an embryo is a life, and I believe strongly that it is life, then no government has the right to sanction their destruction for research purposes," Brownback said in a statement of dissent.

House Minority Leader John Boehner, a Republican from Ohio, also criticized Obama in a statement, saying he had "rolled back important protections for innocent life, further dividing our nation at a time when we need greater unity to tackle the challenges before us."

Obama also issued a presidential memorandum Monday, promising to restore "scientific integrity to government decision-making," a policy change aimed more broadly into all areas of science, such as climate change, to ensure that science is protected from political interference.

"Promoting science isn't just about providing resources it is also about protecting free and open inquiry," Obama said.

"It is about letting scientists like those here today do their jobs, free from manipulation or coercion, and listening to what they tell us, even when it's inconvenient especially when it's inconvenient. It is about ensuring that scientific data is never distorted or concealed to serve a political agenda and that we make scientific decisions based on facts, not ideology."