Rebels in northern Chad were preparing to advance on the capital N'Djamena, a spokesman said on Saturday, following the funeral of President Idriss Deby who died on the battlefield.
Deby's death on Monday, just after he won an election to extend his 30-year rule, shocked the Central African country which has long been a Western ally against Islamist militants.
A military council headed by Deby's son, Mahamat Idriss Deby, seized power after his death, saying it intends to oversee an 18-month transition to elections.
The rebels, known as the Front for Change and Concord in Chad (FACT), came over the border from northern neighbour Libya on April 11 in their thousands, according to analysts' estimates. Last week, they reached as close as 200-300 km (125-185 miles) from the capital, before a pushback from the army and pause to respect Deby's funeral.
FACT have rejected the military transition, calling it a "monarchy", and urged a return to democracy.
"We are preparing to advance ... We don't accept any military government," spokesman Kingabe Ogouzeimi de Tapol told Reuters, without giving more details.
Battle-hardened from years of fighting for Libyan military commander Khalifa Haftar, the rebels could face stiff resistance near N'Djamena, a base for roughly 5,100 French troops fighting jihadists in the region.
FACT, which does not have links to jihadists, said warplanes bombed their command centre on Wednesday, and that France supported the raid with aerial surveillance.
The French army denied that.
At the funeral on Friday, French President Emmanuel Macron, who sat next to Deby's son, pledged to defend Chad. He also called for a transition to democracy.
In N'Djamena on Saturday, streets were busy and markets were open. Military presence was limited to some soldiers with rifles lying in the shade of pickup trucks at main intersections.
Despite the semblance of calm, opposition leaders, labour unions and civil society organisations have denounced the military takeover, while an army general said this week that many officers are opposed to the transition plan.
Succes Masra, a 38-year old opposition leader banned from the April presidential election, on Friday called for a civilian interim president with a vice president named by the military.
Civil disobedience was an option, Masra told Reuters by phone on Saturday, without giving details. "We want to be heard by all means."