The plans were presented to Emirates airline last week, they added, but did not sway the Dubai carrier in its eventual decision to buy Boeing’s 787-10 at this week’s Dubai Airshow.
Billed as Europe’s answer to the 787 Dreamliner, the A350-900 is designed for airlines that want long range.
But for carriers prepared to settle for less range on certain busy routes, the recently introduced 787-10 carries more passengers and is therefore potentially more efficient per seat.
The proposed A350 layout would help to close the seat gap, by moving the pressure bulkhead back by two and a half feet and changing the rest of the layout to leave more space for seats.
Plane manufacturers have already been steadily adding more seats to their existing aircraft models by improving the way the cabins are set out, or by providing denser configurations.
Airbus says the A350-900, which was originally marketed for 317 passengers, now holds 325 in standard layout.
The Boeing 787-10 is a stretched version of the earlier 787-9 Dreamliner and was originally designed to carry 323 passengers. Boeing now says it carries 330 people.
Airbus said it was constantly looking at improvements but declined to discuss details.
“As with all programmes, we are also studying new cabin improvements on the A350 as it offers a versatile and flexible platform,” a spokeswoman said.
“As a leading aircraft manufacturer we always consider future improvements in line with market and customer needs.” (Reporting by Tim Hepher Editing by Greg Mahlich)