By Jan Strupczewski
BRUSSELS (Reuters) - Flights in and out of Belgian airports were halted on Wednesday due to a technical problem at domestic air traffic controller Belgocontrol, although planes could still cross the country at higher altitudes.
European air traffic authority Eurocontrol said the suspension would last until 1730 CET/1530 GMT.
"We have about 40 flights diverted," said a spokeswoman at Brussels Airport, the country's busiest
A vast queue at the airport had formed at the desk of national airline Brussels Airlines as passengers sought to re-book flights.
Passengers already inside an aircraft returned to the terminal and were told it was unlikely their journey would continue before the afternoon, a Reuters witness said.
Belgocontrol said a power surge was the cause of the disruption but the reasons for this were still not clear.
"The surge also took out our emergency generators, which is why we had to clear the airspace," a spokesman for Belgocontrol said.
Eurocontrol is in charge of upper air space, meaning that flights crossing the small western European country but not originating in or heading to Belgium were unaffected.
The French civil aviation authority DGAC said there was no impact on its traffic and that its airports were ready to handle rerouted planes.
Belgocontrol is responsible for controlling the civil airspace from ground to 24,500 feet (about 7,500 metres) above Belgium and for the space between 14,500 and 24,500 feet above Luxembourg.
Antwerp Airport reported some planes had been diverted, all planes were delayed at Liege, and Charleroi -- a hub for low-cost carrier Ryanair -- reported delays and diversions.
Luxembourg Airport showed take-offs and landings on schedule.
Hundreds of flights to and from London were disrupted in December by a technical failure at England's main air traffic control centre.