Budget airline Ryanair are to sue British public-service television broadcaster Channel 4 after they aired a documentary which raised concerns over the company's fuel policies.

'Secrets from the Cockpit’ featured anonymous Ryanair pilots who expressed concern over passengers' safety due to airlines fuel policies. The doc detailed three incidents in which Ryanair  pilots called in emergency alerts due to fuel shortages.

The investigative ‘Dispatches’ program aired on Monday night and featured pilots voicing concerns over the airline's fuel policies.

Before the show was over, Ryanair issued a statement saying it intends to sue Channel 4 for defamation, the BBC reports.

"Ryanair has instructed its lawyers to issue legal proceedings against Channel 4 Dispatches for defamation," it said.

The Irish airline has slammed the documentary, accusing European pilot unions of smearing the airline in their effort to unionise it.

The documentary also used a survey by Ryanair Pilot Group (RPG), a group of pilots seeking union representation, which claims that an overwhelming majority of Ryanair pilots have concerns about work practices and safety – but are too scared to speak up.

Ryanair chief Michael O’Leary said he offered to do an unedited interview with 'Dispatches', but the show declined.

In a separate statement, the Irish Aviation Authority (IAA), the independent safety regulator for Irish airlines, said that it regularly reviewed Ryanair's fuel policy and was satisfied the airline fully complied with European regulations.

Dispatches | Ryanair: Secrets from the Cockpit | Channel 4