Qantas planes flying to Singapore and Hong Kong from Melbourne -- the nation’s second-busiest air passenger gateway -- will stop in Sydney to refuel amid temporary rationing, the carrier said in a statement Friday.

The domestic route between Melbourne and Sydney is one of the world’s busiest. Some flights “may be disrupted” by fuel availability, Virgin said in a separate statement. ExxonMobil manages fuel supplies at Melbourne Airport on behalf of several providers.

“The supply issue has arisen following disruptions in recent weeks to jet fuel deliveries from multiple fuel terminals across Melbourne, which are in the process of being resolved,” Exxon spokesman Travis Parnaby said in an e-mailed statement.

Melbourne Airport, which is also Australia’s largest air freight export hub and the only aviation gateway to operate without a curfew, said it was encouraging Exxon to prioritize the allocation of available fuel to airlines that have limited alternatives, such as long-haul international carriers.

International carriers were advised of “deep fuel rationing” late Thursday, the Board of Airline Representatives of Australia said, adding that the shortage was more severe than those which occurred in 2015.

“The latest jet fuel shortages are the result of taking no action to deal with known and avoidable supply issues,” said Barry Abrams, the industry body’s executive director.

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