The announcement comes amid fears the soldiers trained by EU training Mision in the Central African Republic could be recruited by Russian mercenary group Wagner.
The European Union has suspended its training mission for soldiers in Central African Republic (CAR) because of fears it could get tied up in violations of international law by Russian mercenaries.
"We would need the guarantee that the soldiers trained by EUTM are not employed by the Wagner mercenaries," an EUTM RCA spokesperson told Reuters news agency on Wednesday.
"For the moment, we don't have a response," he said, adding, EUTM will continue to advise CAR forces.
The European Union Training Mission in Central African Republic (EUTM RCA) says it has advised, educated and trained more than 3,400 members of CAR's forces since 2016 as they fight to stabilise a country facing multiple rebel insurgencies.
Its job has been complicated by the presence of hundreds of Russian operatives, including many from the Russian private military contractor Wagner Group, that have arrived since 2018 and have been working in close coordination with the CAR army.
United Nations experts have said that Wagner members in CAR have committed human rights abuses, including summary executions, arbitrary detentions and torture.
The EU imposed sanctions on Wagner on Monday, accusing it of carrying out clandestine operations on the Russian government's behalf.
Russian President Vladimir Putin has said Wagner neither represents the Russian state nor is paid by it.
He has also said private military contractors have the right to work anywhere in the world as long as they do not break Russian law.
The EU has reacted with alarm to reports that Wagner forces could also deploy to Mali to help the government there battle extremist militants linked to al Qaeda and Daesh.
France, the former colonial power in CAR and Mali, has longstanding military ties across Francophone Africa.
Analysts see Wagner's deployments as part of a Russian strategy aimed in part at undermining those.
The United States said on Wednesday it was "alarmed" by Wagner's possible deployment to Mali.
Malian authorities have declined to comment specifically on reports about Wagner but say they have the right to work with any security partner they choose.