* Supply hit by fire at Europe's top refinery, Hurricane Harvey
* Outages, maintenance at Asian producers also curb output
* Q4 could see strongest average profit-margins since Q1 2015
SINGAPORE, Sept 12 (Reuters) - Profits on churning out barrels of gasoil and jet fuel in Asia could keep climbing after marking their highest in nearly two years this month, boosted as demand outpaces supply hit by a string of refinery outages both internationally and in the region.
Royal Dutch Shell shut its Pernis refinery in Rotterdam, the largest in Europe, in late July following a fire, while Hurricane Harvey curtailed refining production on the U.S. Gulf Coast.
Along with refinery outages in Asia, that helped push the profit-margin on producing gasoil, used in heating and as a transport fuel, to its strongest since September, 2015 on Friday, Reuters data showed. The jet fuel margin on the same day touched its highest since November, 2015.
"Inventories for both diesel and jet usually build through September and draw-down in winter, but we have missed a re-stocking window due to Shell's Pernis refinery and Harvey, so we'll enter winter with low stocks," said Nevyn Nah, a Singapore-based analyst at Energy Aspects.
He added that Asian gasoil and jet fuel margins from October to December would likely average at their highest quarterly level since the first quarter of 2015.
GS Caltex, South Korea's second-largest oil refiner, this week said it was unsure when it would be able to restart a middle distillates producing hydrocracker unit which was hit by a fire last month, with exports likely to be crimped. Middle distillates include gasoil and jet fuel.
Elsewhere, Taiwan's Formosa Petrochemical Corp and South Korea's S-Oil Corp have scheduled maintenance at gasoil producing units for September and October, while at least two refineries in Japan will be undergoing maintenance at crude distillation units over the same months.
"There is less supply from South Korea, Taiwan and China, but stronger demand especially from Bangladesh and the Philippines," a Singapore-based trader said. He declined to be identified as he was not authorized to speak with media.
The end of monsoon season in India is also expected to reduce exports of gasoil from the nation as it focuses on robust domestic demand for the fuel, traders said.
In Singapore, oil traders Winson Oil and Unipec have snapped up 11.9 million barrels of gasoil since early last week, according to Reuters calculations from industry data, stoking cash differentials for the fuel.
And appetite for gasoil has also been boosted as the annual fishing ban in the South China Sea was lifted in August, said a second trader.
Meanwhile, North Asian refiners are expected to start stockpiling heating fuel kerosene for winter and reduce their production of jet fuel, which could boost margins for the latter, traders said.
Jet fuel demand-growth is also generally robust in the fourth quarter due to year-end travel. (Reporting by Jessica Jaganathan; Editing by Joseph Radford)