Also, confusion over the names of Niger and Nigeria, two similar-sounding African countries helped to boost oil prices to near $80 a barrel between Thursday and Friday as traders rushed to buy oil after reports of a military coup which they thought was in Nigeria.
Niamey, the capital of Niger remained calm over the week end with reports that the presidential palace was under heavy guard.
After a day of gunfire, explosions and non-stop military music on the radio on Thursday, the whereabouts of President Tandja remained unknown. Reports said lightly armed soldiers patrolled sporadically in Niamey as schools, banks and markets reopened.
The coup leaders, who also included two colonels, took power in the name of what they called the "Supreme Council for the Restoration of Democracy."
Little information has been released about Squadron Leader Djibo, but news reports said a heavily armed unit under his command played a major role in Thursday's coup.
In Addis Ababa, Ethiopia, the African Union condemned the takeover and urged the restoration of constitutional order.
The coup leaders have so far given no indication of how long they plan to hold on to power, but urged citizens and the international community to support their actions.
After the gun battle on Thursday, Boureima Soumana Sory Diallo, a high official at the state media regulatory agency under Tandja, said he did not know where the president was. "They told us he has been taken by the soldiers," he said.
A spokesman for the American Embassy in Niamey, Robert Tate, said: "We've gotten several unconfirmed reports that he is in the custody of the insurgents."
Though he was elected twice, Tandja has faced increasing international opprobrium and opposition at home as he has steadily rolled back hard-fought democratic gains in the past year.
Bidding to stay in power indefinitely, Tandja dissolved the National Assembly and the nation's high court last year, pushing through a new constitution that gave him more power, extended his tenure by three years and removed term limits.
Last week, thousands demonstrated against him, and Thursday's coup attempt followed a year of political tension and uncertainty in Niger, one of the poorest countries in the world.
Meanwhile, confusion over whether the coup took place in Niger or Nigeria, two similar-sounding African countries helped to boost oil prices to near $80 a barrel last week as traders rushed to buy oil.
A Reuters reporter received a flustered phone call from a hedge fund partner who had heard animated discussion in the market about an incident in Nigeria, only to realise that traders had muddled up Africa's biggest oil producer with its neighbour Niger.
"Markets took off at around the same time a Reuters story came out about gunfire erupting in the Niger capital in an apparent coup bid, mistaken by many as being Nigeria," said Tom Bentz, analyst at BNP Paribas Commodities.
Reuters first broke news of heavy gunfire and a coup in Niger's capital, Niamey, on Thursday. Prices jumped to a one-month high of $79.29 a barrel during the day.
Experts say while a coup in Nigeria would almost certainly rock crude oil benchmarks, a coup in Niger - which has yet to produce oil - would almost certainly not, barring linguistic confusion.
But far from being a costly mistake, the decision to buy oil on the Niger coup was a flash of fortuitous genius for some as oil prices continued rising afterwards to within cents of $80 a barrel, spurred by other factors such as tension over Iran's nuclear programme and a weaker dollar.
The Peoples Democratic Party condemned the military takeover in Niger Republic, describing it as an "unwelcome backward step in the progressive march for the entrenchment and sustenance of genuine democratic governance in Africa."
In a statement by its National Publicity Secretary, Prof. Ahmed Alkali, the party said democracy, no matter how imperfect, is better than other forms of government.
"It was our expectation that the situation in Niger Republic should have been resolved without degenerating to military intervention.
"We therefore wish to join the federal government and all lovers of democracy in demanding for an immediate return of constitutional rule in Niger Republic.
"It is never in contention that sovereignty belongs to the people and only the people can choose their leaders," it said.