By Chris Hogg BBC News, Hong Kong

When lit up in the dark, the pigs glow green See the pigs

Scientists in Taiwan say they have bred three pigs that "glow in the dark".

They claim that while other researchers have bred partly fluorescent pigs, theirs are the only pigs in the world which are green through and through.

The pigs are transgenic, created by adding genetic material from jellyfish into a normal pig embryo.

The researchers hope the pigs will boost the island's stem cell research, as well as helping with the study of human disease.

The scientists, from National Taiwan University's Department of Animal Science and Technology, say that although the pigs glow, they are otherwise no different from any others.

Taiwan is not claiming a world first. Others have bred partially fluorescent pigs before; but the researchers insist the three pigs they have produced are better.

In daylight, their eyes and skin are green-tinged

They are the only ones that are green from the inside out. Even their heart and internal organs are green, the researchers say.

To create them, DNA from jellyfish was added to about 265 pig embryos which were implanted in eight different sows.

Four of the female pigs became pregnant and three male piglets were born three months ago.

Green generation

In daylight, the researchers say the pigs' eyes, teeth and trotters look green. Their skin has a greenish tinge.

In the dark, shine a blue light on them and they glow torch-light bright.

The scientists will use the transgenic pigs to study human disease. Because the pig's genetic material encodes a protein that shows up as green, it is easy to spot.

So if, for instance, some of its stem cells are injected into another animal, scientists can track how they develop without the need for a biopsy or invasive test.

But creating them has not been easy. Many of the altered embryos failed to develop.

The researchers say they hope the new, green pigs will mate with ordinary female pigs to create a new generation - much greater numbers of transgenic pigs for use in research.