Lufthansa said it had to cancel about half of its flights to and from German airports on Friday morning because of bad weather and urged travelers flying within Germany to switch to trains.

Europe's second-biggest carrier had canceled 56 domestic or European flights into or out of Germany by 0930 GMT, an airline spokesman said, as snow fell across parts of the country.

"We expect further disruption and cancellations," the spokesman said. "The weather forecast is not optimistic. The situation will certainly get worse."

Lufthansa's domestic and European flights were delayed by up to an hour. But all long-haul flights were expected to take off on time, the spokesman said.

Frankfurt Airport operator Fraport said some 100 flights to or from continental Europe's largest air hub were canceled on Friday because of bad weather in Frankfurt and at other airports.

For flights that were still operating, the average delay was 45 minutes, a spokesman for Fraport said.

"The cancellations are caused first and foremost by bad weather at other airports," which was preventing aircraft from reaching Frankfurt and leading to knock-on cancellations, he said. "We are largely snow and ice free here."

Frankfurt handles about 1,300 to 1,400 flights either to or from the airport per day.

Lufthansa is the airport's biggest airline customer, with its main base at Frankfurt, and operates several hundred flights daily.