Four of the world's largest airlines-U.S. heavyweights Delta, American and United as well as Dubai-based Emirates-said on Monday they had no plans to start hedging their fuel bills despite recent rises in oil prices.

Speaking on the same panel at the Airline Economics conference in Dublin, executives from the four carriers said in response to a query that they had no plans to alter their separate strategies of not hedging their fuel exposure.

The global Brent benchmark briefly climbed above US$70 per barrel earlier this month for the first time in three years.

"We have not hedged since the merger and our philosophy has not changed. We are the largest purchaser of jet fuel and we think we would be bidding against ourselves. The market is quite thin beyond 12 months," Amelia Anderson, managing director and assistant treasurer at American Airlines, said.

"I don't envision our fuel hedging practice to change in the short term," she added.

American Airlines and US Airways merged in 2013.

Michael Nissyrios, vice-president of financing at Emirates, said the carrier had no plans to order narrowbody jets, contradicting recent media reports.

Sister airline flydubai ordered 175 Boeing narrrowbody jets in November and the two Dubai airlines have announced plans to cooperate more closely.

Ted North, managing director of corporate finance at United Airlines, told the conference United was looking at acquiring some second-hand, "mid-life" aircraft.

Such a move would be unusual for the airline which tends to buy new aircraft and operate them throughout their useful lives, financing them through debt.

Any mid-life-or roughly 15-year-old-jets could be acquired via leasing deals, though no decision has been taken. United does not typically take aircraft on operating leases.