The “shadow fleet” of ships that transport Russian oil around the world has expanded to around 600 tankers, according to trading giant Trafigura.

About 400 crude oil vessels, or 20% of the global fleet, have “switched” from mainstream trades to “ostensibly do Russian business,” co-head of oil trading Ben Luckock said in an interview on Bloomberg Television. For oil product tankers, the company sees the level at 200 tankers, or 7% of the world total.

“You had the old days of Iran and Venezuela, and there was a shadow fleet that was relatively small — it would manage the sanctioned barrels,” Luckock said. “This Russian flow is vastly different — it’s huge.”

The European Union has imposed a ban on almost all seaborne imports of Russian refined fuels from February 5, two months after imposing a prohibition on crude oil. The measures will come in conjunction with a cap on the price of Russian petroleum for anyone wishing to access key western services like insurance.

The ban will eventually lift crude and products prices as shipping mileages increase and routes take longer, Luckock said.

“There’s a lot of people talking about how they can be clever and get rid of Russian oil. But it is a vast volume that needs to find a new home,” Luckock said. “I think in the early days maybe that’s okay, but as time progresses there will be difficulties in the products markets.”

Oil prices have edged lower this year amid robust Russian production and weaker-than-expected Chinese crude demand. Many buyers and shippers remain willing to do business with Moscow despite tightening international sanctions. Brent crude futures traded near $80 a barrel in London on February 3.

Crude will trade in a range of $80 to $100 barrel, heading above $90 this summer as Chinese demand recovers, though futures may struggle to break triple-digits, Luckock said.

“We are building a deep inefficiency into an oil market that has spent decades becoming incredibly efficient,” Luckock said. “This will get worse over time.”

Trafigura is doing “very little” Russian oil-products business, in line with current regulations, but the company —  which is one of the world’s biggest commodity traders and until recently had investments in projects with Russia’s Rosneft PJSC — will be keeping an eye on what the EU announces on Sunday.

“We’ve got a group of compliance people and lawyers waiting to see what the rules are,” he said.