However, the cargo of weapons seized on the plane has nothing to do with Ukraine, officials from the Ukrainian state weapons exporter, Ukrspetsexport, told Interfax.

“The cargo has nothing to do either with Ukrspetsexport or its subsidiaries,” a company official stressed.

Meanwhile, according to some media reports, the An-12 plane could belong to the Ukrainian company, Meridian, based in the Poltava region.

The Itar-Tass news agency has reported a comment from Meridian's Director General, Nikolay Minyailo.

He said the reasons for detaining the plane in Nigeria are groundless.

“We had all the permits for this flight, including those from Nigeria's authorities. There were absolutely no violations concerning the plane, cargo or the documents," Minyailo said.

Minyailo added that the cargo did not belong to Ukraine.

"The plane made the flight from Zagreb, Croatia, to Equatorial Guinea and landed in Nigeria for refueling," Minyailo said, adding that the plane had a seven-member crew.

The Ukrainian Foreign Ministry is reported to be trying to clarify the circumstances in which the plane was seized.

And Nigerian officials have, so far, not commented on the incident.