Diplomats of the European Union did not manage to agree on a new package of sanctions against Russia on Wednesday, Reuters reported, citing sources.

According to Reuters, the EU member states were unable to reach an agreement on penalties against Russian coal imports due to technical issues, as it is unclear whether a comprehensive embargo would affect current contracts.

The diplomats will meet again on Thursday.

According to sources, European Union diplomats failed to accept further sanctions against Russia suggested by the European Commission on Wednesday because technical difficulties, such as whether a coal embargo would affect existing contracts, needed to be addressed.

Sanctions must be agreed upon by EU governments, but concerns were expressed at a meeting of EU envoys on Wednesday, according to three sources familiar with the discussions.

It was unclear how the matter would be resolved, while diplomats were hopeful that a solution might be reached at a new gathering of EU envoys on Thursday.

Read more: Brussels considering ban on gas supplies from Russia

Yesterday, a new wave of sanctions was proposed against Russia by the EU executive, which includes a ban on coal imports and blocks all Russian ships from entering European ports. 

"Russia is waging a cruel, ruthless war, also against Ukraine’s civilian population. We need to sustain utmost pressure at this critical point," European Commission President Ursula von der Leyen said in a video address.

The proposal, which happens to be the bloc's fifth planned wave of sanctions against Russia, needs unanimous approval by the EU's 27 member states.