PARIS (REUTERS) - Airbus has stopped sales of a new book that the planemaker had commissioned for its 50th anniversary, to avoid hampering the manufacturer's attempts to win a settlement in a bribery probe, two people familiar with the matter said.

The move is the latest sign of tension in Airbus as it nears the climax of a roughly US$400 million (S$544 million), four-year internal probe carried out in support of an Anglo-French investigation into the use of intermediaries to win jetliner and other deals.

Airbus has already fired more than 100 people over ethics and compliance issues as its probe progresses.

The book, Airbus: The First 50 Years, written by former New York Times journalist Nicola Clark, charts the rise of Airbus against challenging odds to become a European rival to US Boeing and has a chapter focusing on the probe.

Sources said Airbus hoped to present its findings to the UK Serious Fraud Office and France's PNF police by the end of the year. By doing so, they said it would seek more leniency under a system of prosecution agreements that allows for heavy fines rather than charges that might bar it from public contracts.

The two people said Airbus stopped the book's sales because it was concerned its official links to the publication could hamper talks with the authorities or discussions over other litigation as it seeks a fresh start under new management.

Airbus confirmed it had decided not to go ahead with the commissioned book, but denied any link to the bribery probe. It declined comment on the progress of the investigation itself.

"We continue to co-operate in full with the ongoing investigation," an Airbus spokesman said. "The investigation and the book are two separate topics".

Clark told Reuters she was "deeply disappointed with the very belated decision by Airbus to withdraw (the book)".

The book stems from an unusual initiative launched in 2016 under which Airbus granted Clark unprecedented access and full independence to give an unvarnished account of 50 years of industrial co-operation, just as Europe's political unity wavers.

It was published on Amazon's Kindle service on May 29, half a century after Airbus was launched at a meeting of Franco-German founders including Roger Beteille, who died last month.

The book was quickly withdrawn from online sale, and plans to distribute already-printed copies at the Paris Airshow in June were scrapped at the last minute, casting confusion over the company's 50th anniversary celebrations.

But copies have been circulating and a review was published by Leeham News, a website covering the aviation industry.

Airbus said the version seen by the public was a draft.

"The draft wasn't consistent with our ambition for celebrating 50 years of pioneering progress," the Airbus spokesman said.

Clark said Airbus had not described the book as a draft before notifying her of the decision to withdraw it.