The discount for front-month ICE diesel futures to the second-month contract dropped to $3.50 a tonne, the lowest since April, Eikon Refinitiv data shows.

The deepening contango reflects rising supplies in the region after imports from Asia, the Middle East and the US Gulf Coast rose in recent weeks, with more expected in the coming weeks, traders said.

ARA gasoil stocks rose 6.3pc in the week to Thursday on higher imports from India, Russia and the United States, though demand up the Rhine river was fairly strong, said Dutch consultancy Insights Global.

Waterborne June diesel imports into the ARA rose to their highest since January 2018 to nearly 2.4 million tonnes, data from oil analytics firm Vortexa showed

The June figure was 37pc higher than May's total and much higher than the 1.7 million tonne monthly Jan-May average, the data showed.

Shipping companies, refineries, freight derivatives or diesel cracks? Investment funds are placing their bets as the shipping sector prepares for new rules limiting sulphur emissions from ocean-going vessels.