France will not provide any soldiers for Pope Francis's security if he goes ahead with the visit on 29-30 November, sources told Wednesday's Le Monde newspaper.
The 900-strong Sangaris contingent has a clearly defined mission, they say, and that is to provide security for the airport and help evacuation if necessary.
Officials have told the Vatican that the visit is "high-risk", French defence officials at the Africa security forum in Dakar told the paper.
As well as the French troops, there are 9,000 UN soldiers in the CAR, sent there two years ago when virtual civil war erupted between Muslim and majority-Christian militias.
President Catherine Samba-Panza's government is struggling to reestablish order and France reversed a decision to gradually pull troops out a month ago when violence flared up again.
A referendum is to be held on 13 December, to be followed by presidential and parliamentary elections, and the militias are believed to fear the establishment of an elected government.
Not only do the French fear that the Pope's visit could revive sectarian tensions, they also believe that the arrival of hundreds of thousands of Christians from neighbouring countries would be too much for the country's ruined infrastructure.
The Pope hopes to open a "holy door" in Bangui's Notre Dame Cathedral to show that the Church is standing by an "afflicted and tormented" people.