The former Archbishop of South Africa was admitted to hospital last Tuesday due to a "persistent infection".
He has been undergoing treatment for prostate cancer for the last fifteen years, however his charity confirmed his readmission was not related.
A statement from the Desmond and Leah Tutu Foundation website said: "Archbishop Emeritus Desmond Tutu has been re-admitted to a hospital in Cape Town.
"His daughter, the Reverend Canon Mpho Tutu, said the hospitalisation was unrelated to his cancer treatment. His oncologist confirms that his PSA level is pleasingly low.
"He was discharged from hospital last Tuesday, and re-admitted this afternoon after expressing renewed discomfort.
"'His doctors considered it prudent for him to return to hospital for observation. He'll have a few days of bed-rest while his medical dream team brings the situation under control and determines the next course of action, if any. He will stay in hospital until the weekend, at least,' Reverend Canon Tutu said."
