Twenty airlines in the European Union are being asked to justify their claims that the carbon emissions of their flights can be offset, within an EU investigation launched on Tuesday.
The public are more aware about the environmental impact of their travel and "choose products and services with better environmental performance," European Commission Vice President Věra Jourová said in a statement.
The EU executive arms expects "airlines, as well as any other industry operator, to make a responsible use of environmental claims," Jourová added.
Among other things, the commision is concerned airlines are using the term "sustainable aviation fuels" (SAF) without clearly explaining the environmental impact of such fuels.
Another issue is airlines giving the "incorrect impression that paying an additional fee to finance climate projects with less environmental impact" reduces or cancels out carbon emissions.
The European Consumer Organisation (BEUC) alerted the commission and consumer protection authorities in the EU to the practice. Agencies in Belgium, Spain, Spain and the Netherlands are leading the probe.
Airlines have 30 days to respond to the commission's investigation and bring their environmental marketing claims in line with EU consumer law.
If the commission deems the airlines have not addressed the practices raised by consumer authorities then consumer protection agencies can take further action including the use of fines.