Hundreds of passengers were delayed at Hong Kong International Airport on Thursday morning due to a technical issue affecting check-in systems.

Images from the airport showed long queues at check-in desks, including scores of people at the counters of Cathay Pacific Airways Ltd., Hong Kong’s main airline. 

A person familiar with the matter confirmed that Cathay was affected. The malfunction only impacted certain check-in aisles, so not all airlines had issues, the person said.

Airport Authority Hong Kong said in a statement it was conducting a routine test when a problem was found affecting check-in desks in aisles A to E in the southern end of the departure hall. Some facilities had gradually resumed operations by 8 a.m. it said, apologizing for the inconvenience to passengers.

Cathay advised travelers to come to the airport earlier than they would normally due to the slower process.

Lee Cobaj, a travel writer caught up in the delays, shared photos and videos that showed lengthy queues snaking around check-in desks.

“These things happen but the annoying thing is that the staff didn’t let anyone know what was going on,” she said.

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Technical blips are rare at Hong Kong’s airport, which has seen a significant increase in traffic since the government lifted its mandatory Covid hotel quarantine policy in September. Prior to the pandemic, it was one of the busiest international hubs in the world, with over 71 million passengers in 2019. In January, the airport handled 2.1 million passengers, down 68% from the same month in 2019.