Asia's gasoline crack extended gains to reach a three-session high of $4.29 a barrel on Thursday as cutbacks in supply lent support.

Taiwan's Formosa Petrochemical Corp has reduced throughput at two of its residue fluid catalytic crackers (RFCCs) units which produce mostly gasoline, in view of weak fundamentals.

It has since been exporting very low-sulphur fuel oil (VLSFO), feedstock for RFCCs, since the fourth quarter of 2019.

The refiner may also bring forward a scheduled maintenance at one of the two RFCCs by 10 days to March 10, should fundamentals remain weak.

Industry sources said Formosa is not the only refiner in North Asia which has opted to sell VLSFO instead of using it to make petrol.

Gasoline demand was already weak even before the spread of a deadly virus which started in Wuhan, China, with ample supplies seen across regions.

Gasoline inventories in the US for instance rose for a 12th straight week, this time by 1.2 million barrels to hit another new high of 261.2 million barrels in the week to Jan. 24, the Energy Information Administration said on Wednesday.

Singapore's onshore light distillates stocks, which comprise mostly gasoline and blending components for petrol were at a two-week high of 13.056 million barrels in the week to Wednesday, data from Enterprise Singapore showed.

Asia's naphtha crack was also up, touching a two-week high of $92.55 a tonne.

Japan's Idemitsu was looking to buy naphtha for first-half March arrival at Tokuyama but results were not immediately clear.

This came a day after South Korea's Hanwha Total had bought heavy full-range naphtha at premiums of about $19 a tonne to Japan quotes on a cost-and-freight (C&F) basis.

This was down when compared to the Hanwha Total's purchase on Jan. 8 at premiums above $20 a tonne.

Japan's Asahi Kasei Mitsubishi Chemical Ethylene Corp has restarted a naphtha cracker in Mizushima, western Japan, on Jan. 28, following an outage on January 14.

The naphtha cracker has a production capacity of 567,000 tonnes of ethylene a year without any turnaround and 496,000 tonnes with turnaround.

Sinopec Corp's subsidiary refinery and petrochemical complex in Tianjin plans to shut its entire 12.5 million tonnes per year (tpy) or 250,000 barrels per day (bpd) refinery for a two-month maintenance starting in early May.

It's 1-million tpy naphtha cracker will also shut in May.