"I am feeling fine and I am really sorry for the unnecessary worry which has been caused by the reports appearing in today's press. Please do not worry," Harrison said in a statement released by his London lawyer.
Harrison, 58, also confirmed that he was treated at a hospital in Bellinzona for an undisclosed illness.
According to Reuters, the Swiss newspaper Sonntagszeitung reported on Sunday that the former Beatle had been treated for a brain tumor.
"Mr. Harrison successfully completed this course more than a month ago and we foresee no need fir further treatment," said Swiss cancer specialist Franco Cavalli, according to Reuters.
In May, Harrison underwent surgery at the Mayo Clinic in Rochester, Minn., to remove a cancerous growth from one of his lungs.
This was not Harrison's first battle with the disease.
He was treated for throat cancer after finding a lump on his neck in 1997 for which he received courses of radiation therapy at Britain's leading cancer treatment center, the Royal Marsden Hospital.
Harrison has blamed years of cigarette smoking for his illness.
Harrison, known as the quiet Beatle, was almost killed in late 1999 when a crazed fan broke into his home near London, stabbing him 10 times, puncturing one of his lungs. His wife Olivia hit the knife-wielding intruder over the head with a poker and a table lamp.
Michael Abram, 34, was acquitted on grounds of insanity and confined to a mental hospital.