Nigeria has said it will not allow its nationals to be enlisted to fight in Ukraine where Russian forces are bombing cities and rattling neighbourhoods with gunfire.
This follows reports of alleged recruitment of volunteers in the country to fight on the side of Ukraine.
Nigeria's foreign ministry said the Ukrainian embassy had denied any role in the alleged exercise.
But the embassy confirmed that a number of Nigerians had approached it indicating willingness to join the war, according to a ministry statement.
The embassy also distanced itself from claims that it was requesting $1,000 (£800) from each Nigerian volunteer for an air ticket and visa.
"Nigeria discourages the use of mercenaries anywhere in the world and will not tolerate the recruitment, in Nigeria, of Nigerians as mercenaries to fight in Ukraine or anywhere else in the world," the ministry's spokesperson said.
It comes days after Senegal warned against volunteers enlisting to fight against Russians in Ukraine.
It also ordered the Ukrainian ambassador to take down a Facebook post that had called on Senegalese volunteers to enlist to the war.