Asian jet fuel buyers are paying the highest cash premiums for this time of year since 2013 amid a short-term supply shortage, but the values are likely to fade as late summer travel demand slumps in coming weeks and refiners ramp production back up.

The premium for jet fuel cargoes in the Asian trading hub of Singapore JET-SIN-DIF rose to as high as 38 cents a barrel above benchmark quotes last week, taking the differentials to their strongest levels for July-August since 2013. The premiums were at 23 cents a barrel on Tuesday.

Asian refiners cut output during the second quarter as usual for scheduled plant maintenance, while heavy demand for summer air travel provided a seasonal boost to the region's already-thriving aviation market, trade sources said.

"We had around 2.5 months of heavy (refinery) run cuts from May. Runs were still recovering in July ... (and) refineries are not likely to be on max runs until (later in) August," said Nevyn Nah, an analyst at consulting firm Energy Aspects.

Lower runs at refineries in Europe and the United States also helped to tighten jet fuel supplies, he said.

"The tightening of supplies in the second quarter prior to the uptick in (air travel) demand in the third quarter means Europe, for instance, is not going to get its re-supply from the East until late-August."

This has resulted in a supply-driven jet fuel market as demand growth is taking a hit amid the increasing signs of a global economic slowdown, traders and analysts said.

Most of the remaining summer air travel demand will come from Europe and the United States as Asia's major festivals, such as Ramadan, and its school holidays are over, said a Singapore-based jet fuel trader.

"We also need to take note of the flight cancellations that are happening in Hong Kong and ... the latest status on the Japan-Korea relationship," she said, with both having at least a short-term effect on jet demand.

More than 200 flights have been canceled in Hong Kong amid the escalating anti-government protests in the Asian financial center, while South Korea and Japan are currently in the middle of a deepening trade dispute that is disrupting business ties.

The Asia-Pacific region accounts for about 37% of the global aviation market. Its contribution has grown in recent years due to expanding economic growth, new airports and terminals, cheap fares and increased development of airlines' flight networks.

Asia-Pacific airlines carried 1.6 billion passengers in 2018, up 9.2% from the preceding year, the latest data from the International Air Transport Association (IATA) showed last week.