London: British scientists have developed artificial blood in the laboratory which they say is just two years away before being used in transfusions and save millions who die every year due to blood shortages.

Heart transplant, bypass and cancer patients would also benefit from having a guaranteed supply of blood on hand for their surgery, said the scientists behind the "holy grail" of blood research.

According to them, the man-made blood, created from stem cells, would be free of infections that have blighted natural supplies and could be given to almost everyone regardless of blood group, the media reports said.

In the research, a team from the Edinburgh and Bristol University made thousands of millions of red blood cells from stem cells -- "master cells" seen as a repair kit for the body -- taken from bone marrow.

But with the average blood transfusion containing 2.5 million red blood cells, this is not enough. Cellstaken from human embryos in the first days of life are easier to multiply in large numbers, but the researchers have so far not managed to make such realistic blood.

If they crack the recipe, just one embryo could provide all the cells ever needed for Britain's blood supply, the researchers said.

Professor Marc Turner of Edinburgh University hopes to make a supply of cells with the O-negative blood type. This "universal donor" blood could be given to up to 98 percent of the population.

A supply of safe blood would also be a boon in developing countries, where thousands of lives are lost to conditions such as hemorrhages after childbirth.

Prof Turner predicts that in two to three years, he will be ready to inject a teaspoon of man-made blood into healthy volunteers in the first trial in the UK.

Large-scale trials would follow, but the blood could be in routine use in a decade, the researchers said. Within 20 years, it may be possible to produce two million pints of artificial blood a year -- enough to satisfy the UK's medical needs, they said.

Any embryonic stem cells used would be taken from four or five-day-old embryos left over from IVF treatment and donated to the research project.

Critics say it is wrong to plunder an unborn child for "spare parts" to advance medical science.

But Prof Turner said, "There is a lot of regulatory framework to ensure that the cells are being treated with the appropriate respect and being used for genuine scientific and medical reasons and not in a trivial fashion."

He added that a recent European decision to ban the patenting of treatments based on embryonic stem cells means his focus is likely to switch to other sources of cells.

Chris Mason, a regenerative medicine expert at University College London, called the research "fascinating" and said that a safe, ready supply would make a "massive difference" to patients.

And while there are fears other "body parts" made from stem cells can trigger cancer, blood cells should be free of this risk, he added.