U.S. billionaire Warren Buffett says he is seeking treatment for non-life-threatening prostate cancer.

Buffett broke the news in a letter to the shareholders of his investment company, Berkshire Hathaway Inc., on Tuesday.

In the letter, Buffett stated that the disease isn't debilitating and that he "feels great."

The investment guru said that he was diagnosed last Wednesday, and received a CAT scan the following day.

Buffett said that he had an MRI on Tuesday, and that the tests "showed no incidence of cancer elsewhere in my body."

"My doctors and I have decided on a two-month treatment of daily radiation to begin in mid-July. This regimen will restrict my travel during that period, but will not otherwise change my daily routine," he wrote.

"I feel great -- as if I were in my normal excellent health -- and my energy level is 100 percent."

The 81-year-old said the diagnosis came after his PSA (prostate specific antigen) level spiked above its normal level, and a biopsy was done.

"I will let shareholders know immediately should my health situation change. Eventually, of course, it will; but I believe that day is a long way off."

The announcement comes less than a month before Berkshire Hathaway's annual meeting, which occurs at the company's headquarters in Omaha, Nebraska, and routinely draws about 40,000 shareholders.

Recently, there have been rumblings within the company about a succession plan for the so-called "Oracle of Omaha," who has won praise for his prowess as an investor.

As Buffett ages, it's still not clear when and how the company will pick a successor to run the massive conglomerate, which employs more than 250,000 people globally through various subsidiaries.