Responsible shipowners are being forced to spend more time checking the backgrounds of buyers of old secondhand tankers to ensure they do not end up in the dark fleet, trading sanctioned cargoes, says Stena Bulk CEO Erik Hanell.

He said it is “very, very difficult” for owners to ensure that the tankers remain within the mainstream fleet, with some ships sold for scrap returning to trading oil from Venezuela, Iran and Russia.

The head of the Gothenburg-based shipowner, which has a fleet of 64 tankers, said his company is checking buyers to a “high degree” and putting conditions into contracts, but they cannot stop further resales under different terms.