In a statement issued by the White House, Bush said he vetoed the "Stem Cell Research Enhancement Act of 2007" to maintain the current delicate balance of the nation's stem-ell research policy.

"Compelling American taxpayers to support the deliberate destruction of human embryos would be a grave mistake," Bush said. "I will not allow our nation to cross this moral line."

The president said his administration would offer support to technological advancements focused on fighting diseases without creating ethical dilemmas.

Citing past congressional support for such research, Bush asked lawmakers and scientists alike to focus on avoiding controversial methods.

"I invite policymakers and scientists to come together to solve medical problems without compromising either the high aims of science or the sanctity of human life," Bush said.