SINGAPORE--Australian oil and gas company Santos has sold heavy sweet crude Pyrenees at an all-time high premium of more than $10 a barrel as traders continued to stock up the oil ahead of a ship fuel change mandate, three trade sources said on Monday.

The 600,000-barrel cargo loading in late-July was sold to a trading company at a premium close to $15 a barrel above dated Brent, they said.

Pyrenees is one of a handful of Australian heavy sweet crude grades that are being sold at record premiums because of strong demand from traders who are storing the low-sulphur oil to prepare for a surge in ship fuel demand when IMO 2020 kicks in.