The creation of the first part-human, part-animal hybrid embryo in the U.K. by researchers in Newcastle University has raised huge debates and was even called “monstrous” by Cardinal Keith O’Brien, the leader of the Scottish Catholic Church.

The embryos were created by implanting DNA from human cells into eggs taken from cows’ ovaries with virtually all their genetic material removed. They will be used in medical research regarding several illnesses.

The embryos survived for three days, but the future of medical research involving them will be debated by the Parliament.

Even though Cardinal O’Brien called the project “an experiment of Frankenstein proportion,” researchers and patients groups consider it very important for understanding many diseases. They even said the embryos could help them find treatments for diseases such as Parkinson’s and Alzheimer’s.

The team of Newcastle researchers said they had to use cow eggs because human eggs are too precious and also in short supply.

The hybrid embryos will be allowed to grow only 14 days, during which scientists will try to extract stem cells out of them, in order to produce treatments for various diseases such as diabetes.

“This is licensed work which has been carefully evaluated. This is a process in a dish, and we are dealing with a clump of cells which would never go on to develop. It's a laboratory process and these embryos would never be implanted into anyone,” Professor John Burn from Newcastle University told BBC News.

"We now have preliminary data which looks promising but this is very much work in progress and the next step is to get the embryos to survive to around six days when we can hopefully derive stem cells from them," he added, assuring that the research would be completely ethical.

Despite critics from the Roman Catholic Church, claiming the research is immoral, the experiment was approved by the Human Fertilization and Embryology Authority.

Scientists assured the public that the research is not to be compared with cloning or other unnatural genetic experiments, but a vital method of finding treatments for usually incurable diseases.