Trafigura Group could switch more of its crude-oil tankers to carry refined products if sluggish market conditions persist.

About 12% of Trafigura’s fleet of very-large crude carriers (VLCCs) and 20% of its Suezmaxes can carry those fuels on top of shipping denser crude, the trading house’s global head of wet freight, Andrea Olivi, said in an interview. “From what we see in the market today, I would expect this number to potentially increase,” he said.

The conversion, which began in recent months, was prompted by low crude-oil tanker rates amid weaker oil demand from China, Olivi said. He added that production cuts from the Organization of the Petroleum Exporting Countries also meant there was less oil that needed to be transported on tankers.

At the same time, attacks by Houthi militants on merchant vessels in the Red Sea have forced ships to take a longer route to reach Europe from Asia. That’s boosted charter rates for smaller ships that transport fuels like gasoline and diesel as they now need to sail around Africa, adding thousands of miles to their journeys.

VLCCs, with their large sizes and ability to sail longer distances, allow for greater economies of scale, said Olivi. “VLCCs have become the bellwether of the market, they are extremely flexible in adapting,” he said.