The European Court of Justice has ruled in favour of a ban on patent protection for embryonic stem cell lines.

The decision on the ban has been pending since April 2011, and yesterday the court ruled any invention based on human embryonic stem cells is unethical and therefore cannot be patented.

Scientists have expressed their disappointment over the news, including Dr David Hay, Principal Investigator within the Pluripotent Stem Cell Hepatocyte Development at the University of Edinburgh.

He said: "The ruling will have major implications for the commercialisation of stem cell based technologies in the EU and worryingly, create the idea that stem cell research is immoral.

"This will undoubtedly have a negative impact on the clinical translation of the basic and world leading research carried out in Europe and delay the delivery of cutting edge treatments to the patient," added Hay.

A University College London researcher said the ruling casts "real doubt" on the possibility of new medicines from stem cell research.

He explained: "Getting a stem cell technique to cure blindness is fantastic, but it may never get out as a medicine because no manufacturer will get any financial reward from it."