(Corrects number of countries with confirmed flu cases to 15)
Major U.S. airlines including Delta Air Lines, U.S. Airways, Continental Airlines and UAL Corp's United Airlines said they were cutting services to Mexico on Friday, citing lower demand for flights to the country hard hit by a flu outbreak.
Delta, the world's biggest airline, still offers services to all of its 11 destinations to Mexico, spokeswoman Betsy Talton said in an emailed statement.
But the Atlanta-based carrier was making some adjustments to flight frequencies and the type of aircraft flown on certain routes to reduce capacity and ensure it is appropriately matched to demand, the statement added.
Earlier on Friday, Continental and United announced reductions effective Monday in their service to Mexico, which has reported up to 101 deaths from the new strain of Influenza A (H1N1), originally called swine flu.
U.S. Airways said it would cut 38 percent of its scheduled flights to 12 cities in Mexico between May 10 and July 1.
The U.S. carriers join some global airlines that have reduced links to the country. Air Canada has said it was temporarily suspending operations to popular resorts such as Cancun and Puerto Vallarta, and Spain's Air Europa said it would cut charter flights.
Germany's Deutsche Lufthansa AG announced contingency plans to cut flights and drop routes amid the crisis, and said it would place doctors on its planes to Mexico in hopes of detecting any flu infections early.
The World Health Organization says experts do not yet know enough about the new flu strain to say how deadly it is and how long any potential pandemic may last.
Worldwide, 15 countries have confirmed cases.
Chicago-based United said on Friday it would cut flight departures to Mexico by 60 percent in May to just 24 flights a week. In June, United, which has less than 2 percent of its consolidated capacity dedicated to the country, will offer 52 weekly flights.
Continental said it would cut flight departures by about 40 percent and also halve its capacity on flights.
Houston-based Continental offers more seats than any foreign airline into and out of Mexico, according to data provided exclusively to Reuters by airline schedules consultant Innovata.
Prior to these reductions, Continental said it operated an average of 450 weekly flights to the country.
The International Air Transport Association (IATA) warned earlier this week that the flu outbreak would compound financial problems for airlines, which are struggling as the global recession depresses travel demand.
The Amex airline index rose 3.6 percent on Friday.