SINGAPORE, April 18 (Reuters) -
* Australia's Santos has sold a June-loading cargo of heavy sweet Van Gogh crude at more than $9 a barrel above dated Brent, likely the highest premium ever seen for the grade, trade sources said on Thursday
* The buyer for the 400,000-barrel cargo loading on June 24-28 was not immediately known
* Another Australian heavy sweet grade, Pyrenees, has also fetched a strong premium at close to $9 a barrel to dated Brent, traders said
* BHP may have sold the 600,000-barrel Pyrenees cargo loading on June 22-26 to BP (LON:BP), they said
* Energy companies do not typically comment on such commercial transactions
* Spot premiums for these Australian crude grades have surged as traders stock up low-sulphur oil supplies ahead of IMO 2020, traders have said