Ryanair is calling for immediate action to block the “anti-consumer” take-over of bankrupt Air Berlin by rival Lufthansa.

But chief executive Michael O’Leary said the airline would not bid for any of Air Berlin’s assets due to concerns about the sell-off process.

“If there was a fair and open process we would get involved, but we are not getting involved in this process because it’s a stitch-up,” O’Leary told a news conference in Berlin.

He said Ryanair had asked German and European anti-trust authorities to investigate what he said was a “conspiracy” between Air Berlin, Lufthansa and the German government which would lead to higher prices for consumers.

The insolvency is being timed to allow Lufthansa to take over a debt-free Air Berlin, which would be in breach of German and EU competition rules, he argued.

Lufthansa has been supported by the German government providing €150 million of state aid to keep Air Berlin flying.

Air Berlin’s assets, including routes and aircraft, will be sold off piecemeal next month by an administrator.

A takover by Lufthansa would raise the carrier’s German market share up from 68% to a 95% monopoly, which will result in German customers and visitors suffering higher air fares, O’Leary warned.

Competitor airlines will struggle to get slots in major airports such as Berlin, Hamburg, Frankfurt and Munich, where Lufthansa will control more than 80% of peak time slots.

O’Leary said: “The German Bundeskartellamt [competition regulator] and the European Commission must block the anti-consumer stitch-up playing out between the German government, Lufthansa and Air Berlin.

“Given that the German government is centrally involved in these manoeuvres – loaning €150 million – the Bundeskartellamt will be afraid to impose competition rules.

“On this basis, it is vital that the European Commission takes immediate and decisive action to protect German consumers from a Lufthansa high fare monopoly.”

He added: “Ryanair will continue to grow in Germany as more and more German customers choose our low fares and ‘Always Getting Better’ customer service over Lufthansa’s high fare monopoly.”

His comments came as Ryanair joined industry body Airlines UK as an “international airline member”, a new tier of membership that allows non-UK carriers to join the association.

O’Leary said: “As Europe’s largest airline carrying over 131 million customers, we are pleased to join Airlines UK.

“We remain concerned at the uncertainty which surrounds the terms of the UK’s departure from the EU in March 2019 and we understand how critical it is that all airlines come together as an industry to lobby for an effective solution for air travel that allows UK-EU flights to operate after April 2019.

“We look forward to working closely with Airlines UK on Brexit and the many other common issues we face including air traffic control delays, Air Passenger Duty and airport charges.”

Airlines UK chief executive Tim Alderslade said: “Ryanair is the largest airline in Europe with a substantial presence in the UK.

“With so much happening on the policy and regulatory front currently we’re delighted to be able to work more closely with them on issues of mutual interest, including the impact of Brexit on the aviation market access across Europe, campaigning against the damaging and counterproductive Air Passenger Duty, and engaging with industry and government to resolve the growing problem of disruptive behaviour caused by excessive consumption of alcohol.

“Their membership will further strengthen our ability to advocate on behalf of a sector that is such a vital UK and European success story and we look forward to working with them.”