Travellers who are accustomed to reasonable elbow room in the cheap seats will find they have less space. While British Airways has nine economy seats abreast in its 777 fleet at present, from 2018 each row will have 10 seats - even though the average girth of passengers is increasing.

The squeeze is on for British Airways economy passengers on the airline's main long-haul plane. BA is to add an extra 52 seats to its Boeing 777s at Gatwick from 2018, and plans to "densify" aircraft at Heathrow after that. 

Aviation website The BA Source said that accommodating almost a fifth more passengers would necessitate the removal of three toilets. But a BA spokesperson said that the airline "did not recognise" this suggestion. At present the 777s are fitted with 11 toilets.

British Airways is to add 12 extra seats on its short-haul Airbus A320 fleet operating from Heathrow, giving the planes the same seating density as easyJet. Willie Walsh, chief executive of BA's parent company IAG, told investors at a Capital Markets Day: "We're responding to a market opportunity." He said the move would allow BA to "lower the average cost per seat, charge a lower price and stimulate demand".

In the late 1990s, British Airways had a small fleet of Boeing 777 aircraft at Gatwick that were fitted with 10 seats in each economy row for routes to Florida and the Caribbean. In 2002 they were converted to the nine-abreast configuration to match the rest of the fleet.

A spokesperson for BA said: "We are updating our 777 cabins to bring us into line with many of our competitors." Other airlines with a 10-abreast configuration on the jet include Air New Zealand and Emirates. Air France has a special fleet devoted to Caribbean and Indian Ocean services with 10 seats in each row.

BA says that the economy cabin will be fitted with new entertainment systems with bigger screens.

British Airways and its main European rivals, Lufthansa and Air France-KLM, face intense competition from Gulf-based carriers, with low-cost, long-haul airlines such as Norwegian also poaching passengers.

Lufthansa is rapidly expanding its Eurowings subsidiary to operate a range of long-haul routes, while Air France says it plans to start an entirely new airline "adapted to ultra-competitive markets". The subsidiary is intended to "enable the Group to go on the offensive by opening new routes, reopening routes closed due to their lack of profitability and maintaining routes under threat".

Willie Walsh of IAG, which also includes Aer Lingus, added that passengers connecting to the Irish airline's transatlantic services in Dublin could soon be flying on Ryanair. He confirmed to investors that Aer Lingus is in talks with Europe's biggest low-cost airline about feeding traffic to long-haul routes.