The France international's current contract is due to expire at the end of the season and he is unwilling to agree fresh terms.
As a result, Rennes are ready to cash in on the 24-year-old now instead of letting him go for free in the summer.
After scouting him earlier this season, Swansea had been hoping to tie up a deal for Ntep during the current transfer window - while Southampton and Watford have also been linked with him in the past.
However, according to France Football, Wolfsburg are now in pole position to win the race for the Rennes winger.