Chinese refiners are not importing as much crude oil. Poor arbitrage economics, surging outright prices, and pressure on the independent refining sector have reduced the country's demand for long-haul Atlantic basin barrels in recent trading cycles, forcing sellers of these grades to discount and look elsewhere, according to market participants.

India has been looking to procure more North and Latin American grade crudes, Kapoor said.

Ample availability of barges plying the delivered bunkers trade in Singapore stiffens price competition too, another bunker supplier said. Data by the Maritime and Port Authority, or MPA, of Singapore showed a registry of 210 bunker barges as of March 2021, slightly down from the 215 registered barges reported in July 2020.

The second quarter saw significant price increases across distillates and light ends, with outright values reaching 1.5-year highs amid a tightening of the crude oil market and global demand recovery hopes.

Maritime industry players in Singapore are keeping a close watch on bunker fuel quantity disputes, as a slew of pandemic-related restrictions including contactless bunkering potentially reduces the scope for checks on bunker tankers and tough markets may tempt some unscrupulous players to benefit from the situation.