Exhaust-gas scrubbers were “a critical element” in Scorpio Tankers’ decision to buy 19 lease-financed product tankers from Trafigura for $803m, a source close to the deal has confirmed.

Alhough the source stopped short of saying the New York-listed company would not have made the purchase without the cleaning systems installed, he said “they were a very key feature, a very important consideration".