A spokesman for UN Secretary-General Ban Ki-moon said Monday he demanded a South Korean magazine apologize and retract an article that alleged Ban took money from a South Korean businessman more than a decade ago.

"I have written to the author of the article to tell him that Ban Ki-moon has lived his whole life, especially during his distinguished career as a public servant both in the Republic of Korea and at the United Nations, with unblemished honesty and integrity, and that the story that he published is completely false and groundless," Stephane Dujarric, Ban's spokesman, said.

"Despite the clear denials offered by the secretary-general and others, they went ahead and published this story, without any factual validity. I demanded of the journalist that the story be immediately retracted and that an apology be issued," he said.

The Seoul-based weekly magazine Sisa Journal reported over the weekend, citing multiple unnamed sources, that Ban received about $230,000 from Park Yeon-cha, a scandal-ridden local businessman, on two occasions: in 2005 and 2007.

Ban's office strongly rejected the report as "completely false and groundless." Park also dismissed the report as "nonsense." A former senior prosecutor, who investigated Park over a bribery scandal, also said he hadn't heard of the allegations.

Ban, whose second five-year term as UN chief expires Saturday, has effectively declared his presidential aspirations, saying in a farewell press conference with Korean reporters last week that he is ready to give his all if it contributes to the development of South Korea.

Opinion polls have long shown Ban is one of the favorites in next year's presidential election. The election, which was originally scheduled for December, could take place much earlier if the Constitutional Court upholds the impeachment of President Park Geun-hye.

Ban is scheduled to return to Seoul on Jan. 15. (Yonhap)