WASHINGTON, United States of America - Billionaire investor Warren Buffett has completed radiation treatment for prostate cancer, according to a newspaper owned by the larger-than-life financier.

"It's a great day for me. Today I had my 44th and last day of radiation," the tycoon told executives of newspapers he recently acquired on Friday, according to a report on the website of The Omaha World-Herald.

Buffett -- known for his humble manner and modest tastes despite amassing billions as the mastermind and chief executive of investment firm Berkshire Hathaway -- had announced in April that he had an early stage of the cancer and would undergo treatment.

"I'll be feeling the side effects for a few weeks yet, but I am so glad to say that's over," The Omaha World-Herald quoted the 82-year-old as saying.

The Omaha World-Herald Company is owned by Berkshire Hathaway.

Buffett held the number three spot on the Forbes richest list released earlier this year, with an estimated net worth of $44 billion.

Prostate cancer is the most frequent cause of death from cancer in men over 75 years old, according to US official data. But it is relatively slow-growing compared with other forms of cancer. - Agence France-Presse