The African Union has called for an end to military rule in Chad, whose president was killed by rebels.
The army immediately announced that Idriss Déby’s son would head a military council for 18 months before elections were held.
Former colonial power France, which has a large military base in Chad, appeared to back the takeover for stability.
Opposition parties have also condemned what they called a dynastic coup.
Trade union have called for a general strike, while rebel group said Chad was not a monarchy.
The African Union’s Peace and Security Council voiced concern about the military takeover which put 37-year-old General Mahamat Déby Itno in charge and saw parliament dissolved.