A convicted rapist and murderer who has been imprisoned for almost three decades has been granted the right to die after doctors agreed his psychological condition was incurable, a Belgian official said.

Belgium's justice minister approved Frank Van Den Bleeken's transfer to a hospital where doctors will end his life, the official said.

Van Den Bleeken's lawyer, Jos Vander Velpen, told Belgian television his client was "suffering unbearably".

Belgium has allowed euthanasia since 2002 in cases where patients' physical or psychological suffering is incurable and constant. Some 1,400 people a year choose the option.