Continued growth in first and business-class passenger numbers helped boost December traffic at British Airways and Iberia parent International Airlines Group.

IAG said premium travel rose by 13.6% year on year, while non-premium traffic was up 12%.

Passenger carryings were up by 10% to 3.8 million, with North American traffic showing the highest rise at 21% to 630,000. Domestic passenger numbers in the UK and Spain dropped by almost 5% to 758,000.

The overall figures were helped by the non-recurrence of poor weather in December last year, which particularly affected BA.

IAG said: “Underlying market conditions appear unchanged, but there was a significant reduction in Iberia’s short haul premium traffic compared to last year, influenced by the strikes during the month and the weakening economic environment.”

The Iberia pilots’ union went on strike for two days in December resulting in the Spanish airline operating 68% and 64% of its flights on December 18 and 29 respectively.

Budget rival Ryanair carried 4.8 million passengers in December, 5% down on the same month last year as it grounded 80 aircraft to avoid flying routes made unprofitable by high fuel prices.