FRANKFURT (Reuters) - Lufthansa (>> Deutsche Lufthansa AG) and Air France (>> Air France-KLM) were briefly hit by computer problems preventing them from boarding passengers on Thursday evening, airport and airline staff said on Thursday.

A gate agent at Frankfurt airport, Lufthansa's main hub, had announced the airline was having "a computer system breakdown worldwide," preventing passengers from getting on planes, but shortly afterwards was able to resume boarding, a Reuters reporter at the scene said.

The airline said on its Twitter account the systems were back up and running after a global outage.

Twitter users spoke of similar boarding delays at Air France, although they were also quickly resolved. A spokesman for Air France said it was due to a problem with a system from travel technology group Amadeus IT (>> Amadeus It Group SA).

Amadeus confirmed its Altea system had experienced some technical issues, which resulted in flight delays and problems in the booking process.

"All systems are now working normally and the situation is fully recovered. We regret any inconvenience caused to customers and travelers," it said in a statement.

Some North American carriers have in recent months had to ground flights as a result of computer glitches, although such instances have been rare in Europe.

In January for example, United Airlines (>> United Continental Holdings Inc) had to ground all domestic flights for about an hour one Sunday evening, causing a cascade of delays throughout the United States.

Last August, a power outage hit computer systems at Delta Air Lines (>> Delta Air Lines, Inc.) and led to thousands of flights being canceled.

(Reporting by Tim Hepher and Victoria Bryan; Editing by Elaine Hardcastle and Toby Chopra)