Nearly half of Russian seaborne crude shipments were carried in European-owned tankers in October in a sign of the potential upheaval in trade flows that will follow the European Union’s import ban next month, according to data from a Finland research association.

European countries will ban seaborne Russian crude imports from 5 December and prohibit insurance, finance and broking services for shipments elsewhere in the world unless barrels are priced below an agreed price cap.

Details of the price cap have yet to be thrashed out — including the level it will be set — and it remains unclear how many European owners will seek to continue to haul Russian crude.