Russian businessman Yevgeny Prigozhin, an ally of President Vladimir Putin, said on Monday he had founded the Wagner mercenary group and confirmed its deployment to countries in Latin America and Africa.
Prigozhin said in a statement from his company, Concord, that he founded the group to send fighters to Ukraine's Donbas region in 2014.
"From that moment, on May 1, 2014, a group of patriots was born, which later acquired the name BTG Wagner," he said.
Prigozhin, dubbed "Putin's chef" because of his Kremlin catering contracts, has previously denied links with Wagner.
"I myself cleaned the old weapons, figured out bulletproof vests and found specialists who could help me with this," Prigozhin added.
"These guys -- heroes who defended the Syrian people, other people of Arab countries, destitute Africans and Latin Americans -- have become the pillars of our motherland," he said.
Prigozhin, 61, has been hit with EU and US sanctions, accused of being behind a "troll factory" that attempted to interfere in the 2016 US presidential election.
For years, the Wagner group has been suspected of playing a role in realising Moscow's overseas ambitions, with the Kremlin denying any links.
Its presence has been reported in conflict zones including Syria, Libya, Mali, Ukraine and the Central African Republic, where it has been accused of abuses and capturing state power.
Critics say it is Putin's "shadow army", promoting Russian interests by providing fighters, military instructors and advisers.
Wagner's presence was forced into the spotlight in 2018 when independent newspaper Novaya Gazeta reported that several Russian-speaking men who killed and mutilated a detainee on video in Syria were Wagner fighters.
Earlier this month, a video was shared on social media seeming to show Prigozhin recruiting inmates of a Russian prison to bolster Wagner's ranks in Ukraine.
The Russian army has faced difficulties in its seven-month-old military intervention, with Putin last week ordering a partial mobilisation of reservists to regain momentum after Kyiv's forces retook swathes of Moscow-controlled territory in a counter-offensive.
Russian media have reported that Prigozhin controls Wagner's finances, whereas its operations are managed by Dmitry Utkin, a shadowy figure who allegedly served in Russia's military intelligence.
Utkin was received at the Kremlin in 2016 for a ceremony paying tribute to "heroes" who served in Syria and has been photographed with Putin.