HONG KONG • Cathay Pacific Airways made a mistake selling first-and business-class tickets at a steep discount. Now, the lucky few who made the bookings will travel in style after all.

The Hong Kong-based airline said on its Twitter and Facebook pages yesterday that it would still welcome passengers who bought the business-class tickets from Vietnam to Canada and the United States at economy prices earlier this week.

The online ticketing foul-up meant return fares of as low as US$675 (S$920) from Da Nang in Vietnam to New York for seats at the front end of the plane - a small fraction of the original prices.

"We do not want to go back on our promise to our customers," Cathay said on its Twitter account.

"We made a mistake but we look forward to welcoming you on board with your ticket issued."

While the passengers were kept happy, the mistake adds to embarrassments for the carrier, which is struggling to turn its fortunes around as competition intensifies from Chinese and budget airlines.

The gaffe comes on the heels of a sophisticated hack on Cathay's computer systems last year that exposed private information of 9.4 million passengers in the world's biggest airline data breach.

Mr Gary Leff, a travel and loyalty-programme blogger on View From The Wing, wrote on Monday that the Cathay business-class round trip from Da Nang to New York started at US$675 for travel in August.

Yesterday, the same journey cost around US$16,000 for July and September, according to the airline's website. Prices were not available for August.

Travel from Hanoi to Vancouver and back in a mix of business and first class could cost less than US$1,000, according to a post on website One Mile At A Time.

Other airlines have made similar pricing errors previously.

Singapore Airlines in 2014 and Hong Kong Airlines last year honoured business-class tickets mistakenly sold at economy prices.

Both carriers did not disclose how many people bought the cheaper tickets.