A Russian organisation affiliated with the Wagner mercenary group shared a message apparently from its boss Yevgeny Prigozhin, who said the events in Niger were part of the nation's fight against "colonisers".

The Officers' Union for International Security (OUIS), considered by Washington to be a front company for Wagner in the Central African Republic, on Thursday evening shared a message attributed to Prigozhin.

While the voice in the audio message resembles that of Prigozhin, AFP was unable to confirm its authenticity.

Prigozhin has been out of the public eye since the mercenary group's short-lived rebellion against Russia's top military brass last month.

"What happened in Niger is nothing more than the struggle of the people of Niger against colonisers, who tried to impose their own rules of life," the message said.

The message noted "former colonisers are trying to keep the people of African countries in check" and "fill these countries with terrorists and various gangs, creating a colossal security crisis".

"In order to maintain their actual slave system in the territories of these states, they deploy various foreign missions, which number tens of thousands of soldiers," the statement attributed to Prigozhin said.

It added that "these tens of thousands of soldiers are not capable of protecting the population of sovereign states. The population is suffering".