Hong Kong authorities have arrested 27 people and seized more than 21,000 litres of illicit fuel worth about HK$3.3 million (US$421,200) in a crackdown on triad-linked illegal fuel sales amid soaring global oil prices.

Customs, police and fire services on Wednesday said they had jointly tackled 19 cases between April 13 and 30 in an operation code-named “Knockout”, during which 15 vehicles and a speedboat used to transport the fuel were also seized.

The investigation found that the vehicles were used to transport fuel from mainland China to local storage facilities and filling stations run by triads, which then sold it to drivers seeking to exploit price differences.

Of the illicit fuel seized, about 8,000 litres was petrol and 13,000 litres was diesel.

Global oil prices have surged since the US-Israel war with Iran broke out in late February, which led to the closure of the strategic Strait of Hormuz.

Supply disruptions pushed local unleaded petrol prices to among the highest in the region, fuelling demand for cheaper, illegal alternatives.

Consumer Council data showed that the pump price for standard petrol stood at HK$36.77 a litre on Wednesday, with net prices after walk-in discounts ranging from HK$ 23.77 to HK$34.77.