Scientists say stem cells could help provide many cures

Stem cells can come from a variety of sources, but the most controversial form come from human embryos.

Some researchers want to be permitted to create cloned embryos specifically as sources of stem cells.

These cells, which can become any kind of bodily tissue, could in theory provide treatments for a vast range of human diseases.

Testing ethics

On the other hand, some avenues of research require the creation of human embryos just to provide stem cells, an idea which many find disturbing.

If that is considered unethical, what about allowing the use of spare embryos from test-tube baby clinics?

In the US, the Bush administration has made its decision, banning the creation of human embryos solely to provide stem cells - but allowing research on a number of stem cell types which already exist in laboratories.

Some researchers want to be permitted to create cloned embryos specifically as sources of stem cells

The European position is more complex, notably because many countries have their own legislation - and many do not.

Delegates at this week's conference include ministers, officials, scientists, business people and ethicists.

Researchers will describe how stem cells might treat people with Parkinson's disease and diabetes; industry leaders will press for liberal laws; European experts on law and ethics will describe what the current situation allows.

Research into technologies such as stem cells and cloning moves extremely fast, and it has been difficult for legislators to keep up with scientific developments.

This meeting is an important step in clarifying the position which European Union countries will eventually adopt in this most controversial of scientific fields.