Ryanair is cutting services from Stansted in protest against a claimed 6% hike in charges.

The no-frills carrier claims the increase from April is being imposed by owner Heathrow Airport Holdings – formerly BAA – despite the conclusion of the sale of the Essex airport to Manchester Airports Group.

The schedule reduction will see Ryanair passenger numbers cut by 9% from 12.5 million to 11.4 million through Stansted over the next year.

The Irish carrier said it originally planned to grow its Stansted traffic by 5% from April 2013 but will now cut frequencies on 43 routes and reduce its weekly operations by over 170 flights.

Ryanair called on the Civil Aviation Authority to investigate whether the price hike was a ‘sweetener’ in the £1.5 billion sale of Stansted.

A spokesman for the airline, which has been in a long-term dispute over Stansted charges, said: “Ryanair and other Stansted airlines now must ask was this surprise price increase part of a ‘sweetener’ package to persuade MAG to pay £1.5bn for Stansted?”

A Heathrow Airport Holdings spokesman said that, as the sale of Stansted had gone through yesterday, it was no longer in charge of the airport and could not comment.

MAG chief executive Charlie Cornish told the Financial Times he blamed the fall in Stansted passenger numbers since 2007 as much on increased landing charges as the wider economy.

He plans to “enter into commercial discussions with airlines” promptly.

“Our strategy will be geared around incentivising growth,” he said, laying out a 2018 passenger target of 22.5 million from 17 million now.”