IAG made an operating profit of €710 million for the first half of 2016, compared with €555 million for the same period last year, helped by a 4.1% rise in revenue to £10.8 billion and an 18.7% drop in fuel costs. The results were also boosted by IAG’s purchase of Aer Lingus.

But chief executive Willie Walsh warned that the weak pound since the result of the EU referendum last month had already caused a “negative currency impact of €148 million” for IAG.

Walsh added: “Numerous external factors affected our airlines including the impact of terrorism, uncertainty around the UK’s EU referendum and Spain’s political situation and increased weakness in Latin American economies.

“This led to a softer than expected trading environment, especially in June. In addition, the airlines’ operations have been considerably disrupted by 22 air traffic control strikes in Europe so far this year. This has impacted our passenger revenues.”

IAG is expecting air traffic disruption to cost the company at least €80 during the rest of this year – mainly due to the effect on its Spanish low-cost subsidiary Vueling.

British Airways made an operating profit of €631 million for the half-year – up from €488 million in 2015 - despite revenue falling from €7.4 billion to £6.9 billion over the same period.