singapore march 1 reuters  asian jet fuel refining margins rose on tuesday despite firmer feedstock crude prices buoyed by a gradually recovering aviation demand refining profit margins or cracks for jet fuel jumped to 1604 a barrel over dubai crude during asian trading hours their strongest in three weeks they were at 1423 per barrel a day earlier cash premiums for jet fuel rose to a twoweek high of 166 a barrel to singapore quotes on tuesday compared with a premium of 131 per barrel on monday the marchapril time spread widened its backwardated structure on tuesday to trade at 213 per barrel compared with 191 a barrel on monday  global supply chains already hit hard by the pandemic are facing further disruption and cost inflation as airspace closures after russias invasion of ukraine affect the air freight industry read more  transport between europe and north asian destinations like japan south korea and china has become particularly problematic due to reciprocal airspace bans that bar european carriers from flying over siberia and russia airlines from flying to europe  airlines are bracing for potentially lengthy blockages of key eastwest flight corridors after the european union and moscow issued titfortat airspace bans and washington did not rule out similar action in response to russias invasion of ukraine read more  russia on monday banned airlines from 36 countries including all 27 members of the european union after eu ministers agreed to refuse entry to russian airplanes including the private jets of the countrys oligarchs  oil prices surged on tuesday as concerns over supply disruptions after russias invasion of ukraine and related sanctions outweighed talks of a coordinated global crude stocks release  shell shell will exit all its russian operations including a major liquefied natural gas plant it said on monday becoming the latest major western energy company to quit the oilrich country following moscows invasion of ukraine read more