The Scottish Premier League side are due to meet 20-year-old Ki's representatives later today in London ahead of Wednesday's Champions League meeting with Arsenal.
"Celtic have informed us of their intentions about Ki Sung-yong," Seoul's general manager Kang Myong-won told Sports Seoul.
"We understand that the player may want to move but this is not a good time for us to sell."
Seoul are currently six points clear at the top of the K-League and will face Qatar's Umm Salal in the Asian Champions League quarter-finals next month.
Scottish Premier Winner 2009/10 Win Outright: Celtic 8/11
Source: Team_Talk