The pilot of a flight that was diverted to Belarus, allowing the arrest of an opposition journalist, had been warned that a bomb would detonate if it continued to Lithuania, according to Ryanair's boss.
Michael O'Leary said the pilot tried to seek advice from the airline, but was given false excuses by officials that Ryanair was not answering the phone, reports the BBC.
He called the incident "a premeditated breach" of global aviation rules.
Belarus denies it was a forced landing.
Journalist Roman Protasevich and his girlfriend Sofia Sapega were arrested after the plane landed in Belarus's capital Minsk. Both remain in prison.
Ryanair flight FR4978 was travelling from the Greek capital, Athens, to Vilnius in Lithuania on Sunday 23 May when it made an abrupt change of course over Belarus, some 10km (six miles) from the Lithuanian border