A group of 29 scientists, including three Nobel laureates, sent a letter to the government protesting a donor consent requirement for the use of cloned embryonic stem cells, The Daily Telegraph reported Monday.

The scientists say the requirement set out by the Human Fertilization and Embryology Bill moving through Parliament would deny them access to tissue banks. The banks serve as libraries of genes that trigger the serious diseases scientists want to study.

Much of the tissue currently stored in the banks was collected before it became possible to clone embryos so the patients would not have been able to give their consent.

"For scientists to clone human embryos without the consent of the cell donors, which contains the genetic materials, would be completely unethical," says Dr. Calum MacKellar of the Scottish Council on Human Bioethics.