President Barack Obama will lift his predecessor's restriction on federal funding of human embryonic stem cell research on Monday and will give the National Institutes of Health four months to come up with new rules on the issue, officials said on Sunday.

Obama will not lay out any guidelines himself but let the NIH decide when and how it is ethical and legal to pay for embryonic stem cell research, science adviser Dr. Harold Varmus said.

Researchers and advocates have been invited to a White House ceremony at which Obama will make the announcement, Melody Barnes, director of Obama's domestic policy council, said on Sunday.

He will also sign a pledge to "restore scientific integrity in governmental decision making," Barnes said.

Stem cells are primitive, long-living cells that are the source of all other cells in the body.

When taken from days-old embryos they are virtually immortal and can give rise to all the other cells and tissues in the body.

Supporters say they can transform medicine and have been working to use them to repair severed spinal cords, regenerate brain cells lost in cases of Parkinson's Disease and restore the tissue destroyed by juvenile diabetes.

Opponents, however, say the government should not fund research predicated on the destruction of human embryos.

Agencies