He criticised them for spending more time arguing with each other in public than addressing the enormous problems that affect the country, where sectarian tensions between Christians and Muslims following the toppling of previous president François Bozizé.
The military chief of Bozizé's MRPRC, Joachim Kokaté, was also invited to N'Djamena and told RFI he intended to call for Bozizé to go.
Sources have told RFI that Bozizé met European, African and American diplomats on Sunday and told them he wanted to resign but CAR officials denied that either he or Tiangaye intended to go.
French Foreign Affairs Minister Laurent Fabius on Thursday welcomed the Eccas initiative, saying that "there are certainly some decisions to be made", given that the state is "paralysed".
Fabius confirmed that France will send no more troops above the 1,600 already in the CAR and called for support from European and African countries.
Rwanda on Wednesday announced that it will send 800 soldiers to join the 4,000-strong African force in the CAR, Misca.
The EU is considering proposals to send a military force to the crisis-racked country, following an appeal from France in December to support its intervention there.
Although the widespread violence of recent weeks has subsided in Bangui, shots are fired every night and reprisals between the two camps are reported to be continuing.