Budget airline easyJet is to upgrade and expand its aircraft fleet under a deal to buy 135 Airbus planes over the next nine years.

The no-frills carrier said today that the new 180-seater A320 planes will allow it to boost the number of passengers it can carry from 60million a year to around 90m.

Its new aircraft will also be more fuel-efficient, which means they cost less to run and are more environmentally friendly.

The move will allow easyJet to replace around 85 of its current 211-strong fleet of 156-seater planes, as well as giving it the room to expand and add routes. It also has the option to buy a further 100 Airbus planes as part of the deal.

But the scale of the fleet acquisition means easyJet must get shareholder approval, with the backing of 50% of investors required, and is likely to reignite the long-running row with founder and largest shareholder Sir Stelios Haji-Iaonnou.

Sir Stelios, who with his family controls a near-37% stake in easyJet, has been a vocal opponent of the group’s plans to increase its fleet.

He said earlier this year that he believes the new planes are not necessary and will be acquired at the detriment of shareholders.

Luton-based easyJet, which also operates out of Stansted and Southend airports in Essex, has ordered 35 current generation A320 planes for delivery between 2015 and 2017 and 100 new generation A320neo aircraft from 2017 until 2022.

It said it secured a steep discount for the planes, but did not disclose the cost of the deal.