Troops loyal to Burkina Faso's deposed government said they were preparing to attack the Camp Naaba military base near the capital's presidential palace, which is held by troops who staged a coup last week.
Loyalist troops have been massing in the capital on Tuesday and have told those behind the coup, which derailed a democratic transition process, to disarm and surrender by 10am (10am GMT) or face attack.
As the deadline expired, ex-spy chief General Gilbert Diendere held a press conference, saying he was still in charge and that he was awaiting the outcome of a ECOWAS summit in Abuja, Nigeria, where African leaders were discussing developments in Burkina Faso.
"I'm not stalling for time. I'm within the time alotted to me," he told a news conference, reiterating that he was still president of the National Democratic Council, as his group is known.
IN PICTURES: Burkina Faso coup and violent protests
Al Jazeera's Nicolas Haque, reporting from Ouagadougou, said the situation in the capital was tense even as the country's state TV channel was showing a wildlife documentary.
"Minutes before the deadline expired, General Diendere called a press conference and released a statement saying he wants to stand by the framework agreement that was negotiated with ECOWAS," Haque reported.
"The civil society and most of the people here don't agree with this agreement. On the street right now people are following the orders of the military. The military has asked the people to retreat back home.
"The presidential guard has locked down the presidential palace. They are out in full force. They have also positioned themselves around Burkina Faso's public television and radio station which is currently running [an] animal documentary."
In an apparent olive branch, the coup leaders released interim prime minister Yacouba Isaac Zida, who had been held hostage since the revolt began, his adviser and another loyalist officer said.
Diendere and his presidential guard rebelled on Wednesday, raiding a cabinet meeting and detaining the president and other ministers.
The release of Zida came hours after army soldiers entered Ouagadougou without resistance.
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Diendere, who is a close ally of deposed long-term president Blaise Compaore, already had vowed to hand over power to a civilian transitional government, but not to the army.
Army leaders began surrender talks late on Monday with the elite presidential guards that staged the coup.
"All units [of the army mobilised on Monday to march on the capital] reached Ouagadougou" overnight, Colonel Serge Alain Ouedraogo, deputy head of the Burkinabe police, told the AFP news agency.
"We must now secure the surrender of the [coup leaders] without gunfire or bloodshed," he said.
At least 10 people have been killed and more than 100 injured in protests sparked by the coup, which came just weeks before what would have been the first elections since Compaore was ousted in a popular revolt last October after trying to extend his 27-year grip on power.
Diendere on Monday apologised to the nation and said he would hand over control to a civilian transitional government after the military warned that its forces would converge on the capital and forcibly disarm the soldiers behind the power grab.
He said his presidential guard unit "confirms our commitment to giving power back to civilian authorities", in a communique issued to journalists. That was one of the key conditions of a draft agreement that resulted from weekend negotiations with regional mediators, but it had been unclear until his announcement whether the coup leaders would abide by those terms.
After the announcement Haque said people were taking to the streets by the military headquarters to celebrate what they hoped meant the end to the coup and the chance of elections later this year.
Source: Al Jazeera And Agencies