Nelson Mandela being helped off a plane recently

They decided that due to the good response, the same radiotherapy would be continued until the end of its seven-week course.

The tumour is said to be "microscopic" and should not reduce Mr Mandela's life expectancy.

No surgery is being contemplated for the 83-year-old elder statesman at the moment.

Jail

The Nobel peace prize winner was probably the world's best known political prisoner, spending 27 years in jail.

In 1985, while in prison, Mr Mandela was hospitalised for prostate surgery and had some tumours removed. They proved to be benign.

He then returned to jail, where he remained until February 1990.

As president of South Africa between 1994 and 1999, he supervised its transition from white minority rule to full democracy.

Prostate rates rising

The prostate is a small gland lying close to the bladder.

Prostate cancer is a common condition in elderly men and can usually be treated successfully, if it is detected at an early stage before it spreads to other organs.

It is the fourth most common global cancer, and may become the most common as the world population ages.

Archbishop Desmond Tutu is another sufferer from the cancer in South Africa, where the incidence rate is 42.78 men per 100,000 of the population.

Just under 26 men per 100,000 of the population die from the disease.