Carriers can easily mask the origins of Russian oil shipped to sanctions-averse buyers, sparking concern the products are entering Europe, per the Guardian.
Petrol and diesel prices soared in the UK including in Europe amid the Ukraine war as UK's RAC motoring group called it "a truly dark day".
The Boris Johnson government said the surge was mainly due to the pandemic and the Ukraine war even as the RAC called on the government to slash sales tax on petrol and diesel.
Petrol now costs 182.31p per litre and diesel 188.05p per litre in the UK. The situation worsened after President Putin declared war on Ukraine in February as Western nations moved to boycott Russian oil.
Russia said Wednesday it was moving to limit the damage from an EU oil ban as its other key energy export, gas, has fallen after President Vladimir Putin sent troops to Ukraine.