Annual operating profits at International Airlines Group soared by 65% to €2.3 billion helped by the acquisition of Aer Lingus.

However, the parent company of British Airways, Iberia and Vueling – which took over the Irish carrier in August – saw passenger revenues trimmed in the fourth quarter due to the adverse impact of the Paris terrorist attacks in November.

Passenger unit revenue for the three months was up 3.1%. Excluding Aer Lingus and at constant currency, revenue was down 3.7% including an approximate single point adverse impact from the Paris attacks, IAG said.

The fourth quarter operating profit came in at €540 million, excluding Aer Lingus and before exceptional items, against €260 million in the same period a year earlier. Including Aer Lingus, the figure was €530 million.

Revenue for the full year was up 13.3% to €22.8 billion while fuel costs dropped by 6.3% before exceptional items. Non-fuel unit costs for the year before exceptional items were up 4.3% and down 3.9% at constant currency.

IAG’s passenger load factor was 81.4% – higher than the Iata average of 79.7% and one point higher than the previous year. BA’s operating profit was up by £400 million to £1.3 billion on a capacity increase of 2%.

Aer Lingus produced an operating profit of €124 million, up €72 million, excluding exceptional items, as capacity increased by 5.4% with a focus on long haul routes.

Looking forward, IAG expects to generate an absolute operating profit increase similar to 2015.

Revenue trends in the first quarter of the current financial year appear broadly in line with those in the final three months of 2015.

Chief executive, Willie Walsh, said: “We’re reporting very strong full year results with an operating profit before exceptional items of €2,335 million including Aer Lingus.

“Aer Lingus has made a positive contribution of €35 million operating profit since it joined the group on August 18 last year. These results are in line with our recent target and have exceeded our original 2015 operating profit target of €1.5 billion that we set in 2011.

“It’s undoubtedly been a good year but it’s also been challenging with extreme volatility in the currency and fuel markets. The benefits gained from lower fuel prices have been partially offset by the stronger US dollar.

“In the quarter, we made an operating profit before exceptional items of €530 million including Aer Lingus.”