Former South African archbishop Desmond Tutu has been admitted to a Cape Town hospital for tests.
The Nobel laureate is in good spirits and hopes to go home in a few days, his office said.
Mr Tutu has been treated for prostate cancer for many years.
Last week, Mr Tutu said in a statement that terminally ill people should have the right to a “dignified assisted death”.
The statement followed a murder charge against a local campaigner for the legalisation of euthanasia.