The UK is among many Western countries to ban the import of all oil and oil products that originate in Russia in a bid to hit the amount of cash Moscow can generate from fossil fuels.

But two separate reports, shared exclusively with the BBC, suggest the rules on refining enable products made from Russian crude oil to arrive on UK soil.

The Centre for Research on Energy and Clean Air (CREA) said this “refining loophole” meant countries such as India and China, who have not sanctioned the Kremlin, are able to legally import Russian crude and refine it into oil products such as jet fuel and diesel.

They then export those products to the likes of the UK and the EU.

“The issue with this loophole is that it increases the demand for Russian crude and enables higher sales in terms of volume and pushing up their price as well, which increases the funds sent to the Kremlin’s war chest,” said Isaac Levi, head of CREA’s Europe-Russia policy and energy analysis.