Travelers will have to pay up to $10 more for a roundtrip ticket on UAL Corp's (UAUA) United Airlines and $14 more on Continental Airlines, as the airlines seek to offset the rising cost of jet fuel.

United raised domestic fares by $2 to $5 each way, a spokeswoman for the No. 2 U.S. airline said.

Continental, the No. 4 U.S. carrier, raised its domestic fuel surcharge by $2 to $7 each way, spokesman Dave Messing said.

Last week U.S. airlines, led by Delta Air Lines Inc. (DAL), initiated a fare increase of $5 each way that has largely held.

Most attempts to raise ticket prices so far this year have been rolled back amid competitive pressure as air travel demand softens.

U.S. airlines are struggling to adapt to historically high jet fuel prices. Softening demand makes passing on those higher costs to customers more difficult.