Most U.S. airlines, trying to offset record high jet fuel prices, have boosted air fares in North America by as much as $10 on round-trip flights.

On Wednesday, American Airlines said it increased fares by $5 effective immediately each way for most trips in North America to help offset the cost of jet fuel.

Most U.S. airlines have mostly or partially matched the fare increase. Among those are Delta (DAL) and United.

However, discount airlines Southwest Airlines (LUV) and JetBlue (JBLU) have not matched the increase.

Attempts to raise fares have been short-lived because of the intense price competition in the industry. Previous attempts this year to boost fares to offset high fuel prices failed when other carriers did not follow suit.

Industry sources said the recent fare increases will likely stick at least through the weekend.

Jet fuel is the second-highest operating expense for most airlines, after labor. Fuel comprises about 12 percent to 14 percent of the operating costs for a typical airline.

Struggling U.S. carriers have said their finances have been hammered by the jump in jet fuel prices this year.

American, a division of AMR Corp. (AMR) and the world's largest carrier, has said it would incur more than $1 million in added expenses because of high jet fuel prices.