USA: Scientists have discovered a new source of stem cells that could help repair the body.

Researchers said today that fluid surrounding human embryos contains the cells that can be grown into any type of tissue.

The idea of using stem cells is controversial because the best source is human embryo tissue.

Some campaigners argue that creating embryos for research leads to the destruction of human life.

Now scientists at Wake Forest University School of Medicine in North Carolina and Harvard Medical School have found a small number - around 1% -of stem cells in amniotic fluid.

The cells, which have the potential to become almost any type of tissue, were grown into muscle, bone, fat, blood vessel as well as nerve and liver cells.

Professor Anthony Atala, director of the Institute for Regenerative Medicine at Wake Forest, said: "Our hope is that these cells will provide a valuable resource for tissue repair and for engineered organs as well.

"These cells are capable of extensive self-renewal, a defining property of stem cells. They also can be used to produce a range of cells that may be valuable for therapy."

Last week, British scientists said research into diseases such as Alzheimer's and diabetes was in jeopardy as they waited to see if they will get approval to create embryos that are part animal-part human using eggs from cows or rabbits.

At present, scientists rely on eggs left over from fertility treatment for their research, but these are in short supply.

Today's research, published in the journal Nature Biotechnology, was based on harvesting stem cells from amniotic fluid taken during tests used to diagnose genetic disorders before birth.