United Airlines has raised fares in North America by up to $30 round-trip, the company said Thursday, citing record high prices for fuel. U.S. airlines have announced several fare increases, fuel surcharges, and fee increases recently as they seek to offset higher fuel prices and a weakening U.S. economy. “The fare increases will help us offset record-breaking fuel costs,” a company spokesman said. Rick Seaney, the chief executive of fare tracker FareCompare.com, said United Airlines' move was the 11th attempted fare increase by major U.S. carriers this year. Seaney said United's latest increase “means that many travelers will be paying up to $130 round-trip more than they did in the first week of January 2008 for domestic airline tickets.”