A Nobel Prize-winning scientist says he has resigned as an external member of the Hungarian Academy of Sciences to protest the "repressive policies" of Hungarian Prime Minister Viktor Orban's government.

Torsten Wiesel, a co-winner of the 1981 Nobel Prize in Medicine, joins four other foreign scientists who also have renounced their positions as external members of the academy.

Wiesel, a neurobiologist, confirmed his resignation in an email Thursday to The Associated Press.

Some of the others include Thomas Jovin from the Max Planck Institute for Biophysical Chemistry in Germany and Hungarian-born cognitive scientist Stevan Harnad from the University of Southampton.

They said in a statement that "in Hungary today democracy is under a dark cloud that is seriously threatening freedom of expression, human rights and even the rule of law."