The bodies of 11 Nigerien soldiers missing since Tuesday’s ambush have been discovered, bringing the death toll to 28.
Militants killed four US soldiers at the same place in 2017.
Niger and other countries in the Sahel have been facing a growing militant threat from several Islamist groups.
The Islamic State group has said it was behind the ambush but there has been no confirmation of this claim by the authorities.
Militants belonging to affiliates of al-Qaeda are also active in the region.
They are most active in neighbouring Mali, where French troops intervened in 2013 to prevent them from advancing on the capital, but they often stage cross-border raids.
How did the attack happen?
The soldiers were in pursuit of militants who attacked a high security prison 50km (30 miles) on Tuesday outside the capital, Niamey, a government spokesman told the BBC.
“One of the soldiers’ vehicles drove into a landmine and then the assailants started firing at our soldiers,” Mr Zakariyyah told the BBC’s Focus on Africa programme on Tuesday.
It was initially reported that 17 soldiers had been killed in the ambush.
Without providing any evidence, the Islamic State group has claimed responsibility for the attack via its news agency Amaq. According to the statement, 40 were killed and injured, although for now the government has said that the death toll was 28.
Mr Zakariyyah did not identify the perpetrators of the attack but said it happened near where US troops and five Niger soldiers were killed two years ago.
A search operation, aided by French and American troops, who have a base in Niger, continues.
Niger is part of a five nation anti-insurgency force operating in the Sahel. It includes Burkina Faso, Chad, Mali and Mauritania.
The G5 Sahel, as it is called, is backed by a 3,000-strong French force.