The EU on Friday said it "deplored" a decision by Russia to add a number of EU officials to a list of people banned from entering the country.
Russia's foreign ministry earlier on Friday said the measure was a reciprocal penalty, at a time of heightened tensions between Brussels and Moscow over the Ukraine conflict.
"The European Union deplores the decision by Russian authorities... to ban an unknown number of representatives of EU member states and institutions from entry into Russia," an EU spokesperson said in a statement.
"This decision lacks any legal justification and transparency and will meet an appropriate response," the statement added.
The Russia foreign ministry said the measure also targeted "European private military companies operating in various regions of the world", signalling that the bans were also intended as a response to EU sanctions linked to the Wagner company.
In December, European foreign ministers agreed to slap sanctions on targets linked to Wagner -- a secretive company accused of acting to destabilise Ukraine and parts of Africa.
The EU says the group works on behalf of the Kremlin in conflict zones.
The tit-for-tat sanctions come as the West has warned Russia of a massive coordinated response if it launches an attack on neighbouring Ukraine.