Rennes are currently languishing two points clear of Ajaccio, who are third from bottom, and are keen to reinforce their squad for the remainder of the campaign.
Jeunechamp, who lost the captaincy at the club earlier this term, has been a virtual ever-present for Bastia this season.
"It is a risky move as I am leaving a club in difficulties for another team in trouble," said Jeunechamp.
The news of his impending transfer came as a massive shock to the midfielder, as the club never mentioned any of the rumours to him.
"I was a little surprised by the news, as no Bastia official came to see me to discuss the rumours that are in fact true," added Jeunechamp.
