Ki has made it clear he wants to move on and it is believed English Premier League side Swansea are in talks with the Glasgow club to seal his signing for a fee of around ?6 million ($9.4 million, 7.6 million euros).
The 23-year-old has not returned to Celtic since playing for South Korea at the London Olympics and was absent again on Monday as Neil Lennon's squad flew out for the first leg of their Champions League play-off clash with Helsingborg in Sweden.
Ki, who cost Celtic ?2 million from FC Seoul three years ago, has previously suggested he could be tempted to leave if he got the right offer from a Spanish club.
Celtic had already rejected an offer for Ki from Russian outfit Rubin Kazan in the close-season.
Assistant manager Mjallby said: "Ki is not travelling. He is keen to move on and the club is in discussion with another club, so we have to wait and see what happens. I can't say who the club is.
"There have been a few clubs interested in him but I know for sure there has been one bid for him and I think maybe one or two other bids. He is a quality player but on the other hand he is keen to move on, so the club needs to do something.
"He was away at the Olympics for a period of time but we will be sorry to see him go."
Ki, who helped South Korea win Olympic bronze, played a key role as Celtic won the Scottish title last season and the Scottish Cup in 2011.
Asked if Celtic had a replacement in mind for Ki, Mjallby added: "He has not really been a part of the season so far, so we have shown that we can live without him. But on the other hand, it would be nice to get someone else in if he goes away.
"If quality players leave the club, you want to freshen things up and have competition. But even with Ki here we would like to see some other faces."
Source: AFP
Source: AFP