In an article published on Tuesday, the Södermanlands Nyheter (SN) newspaper described "stressed-out pilots who are forced to fly for free", based on accounts given to the paper by Ryanair pilots who wished to remain anonymous.
The pilots described Ryanair as having a "culture of fear" that resulted in pilots choosing not to take sick leave out of fear they might get fired.
"I don't know how many times I've flown with colleagues that are so tired that they can't keep their eyes open and need to sleep for ten minutes during a flight," one pilot told SN, explaining he wasn't describing scheduled "power naps".
Part of the problem, according to the pilot, is that Ryanair pilots are paid for flight times laid out in a schedule. If a flight is delayed, and a pilot ends up flying outside the time allotted according to the schedule, the pilot in essence flies without getting paid, the pilot claimed.
In an email to SN, portions of which were published by the paper, Ryanair spokesman Robin Kiely rejected the allegations, claiming the anonymous pilots had "made up a bunch of garbage".
Kiely explained that all Ryanair pilots are legally obligated to file a report if they are too sick to fly and denied that a pilot had ever been fired for calling in sick.
He also rejected the pilot's claims that colleagues fell asleep in the cockpit, calling them "untrue, false, and completely made up".
Kiely tried to stop the publication of the article, suggesting that Ryanair would sue SN if it ran the story
"If you publish some of these claims we're going to launch legal proceedings against your newspaper," he wrote.
The efforts to muffle the newspaper left editor Göran Carstorp incredulous.
"It's completely unbelievable. They want to silence a debate about the safety of flying," he told Sveriges Television (SVT).
A representative for the Swedish pilots' union Svensk Pilotförening told SVT that the account published by SN is in line with information he's heard from other Ryainair pilots, adding that some have secretly joined the union.
"The company has a tyrannical construction and works to frighten its employees," union representative Anders Kjellgren told SVT.
"That's why it's so cheap to fly with Ryanair."
Follow The Local on Twitter