The ban is likely to create a diesel supply shortfall that Europe hopes to fill with Chinese fuel, some of which will be produced from Russian crude.
China has raised its first batch of 2023 export quotas for refined oil products by nearly half from a year ago.
"But without Chinese exports pushing swing barrels westward, Europe is unlikely to replace the 0.5 million bpd loss in Russian diesel exports come the embargo," Energy Aspects analysts said.
Russia has long been the main diesel supplier for Europe, where refineries do not produce enough to meet domestic demand from its large diesel car fleet.
Reuters GraphicsAn EU ban on Russian crude imports that took effect in December will be broadened to include refined fuels from Feb. 5.