DUBLIN, July 27 (Reuters) - Digital rights group NOYB on Thursday filed a complaint against Ryanair, alleging that it is violating customers' rights to data protection by using facial recognition to verify their identity when booking through online travel agents.

NOYB, led by Austrian privacy activist Max Schrems, filed the complaint with Spain's data protection agency on behalf of a complainant who booked a Ryanair flight through the Spanish-based online travel agency eDreams ODIGEO..

The Irish airline, Europe's largest by passenger numbers, says on its website that it needs to verify the identity of passengers' booking with travel agents because agents often do not provide Ryanair with customers' contact and payment details.

Passengers can avoid verifying through facial recognition by showing up at the airport at least 2 hours before departure or submitting a form and picture of their passport or national ID card in advance, a process Ryanair said can take seven days to complete.

The low-cost carrier said the steps are required to manage the passenger's booking, online check-in and to comply with safety and security requirements. A similar process is not required when booking through its website or mobile phone app.

"There is no reasonable justification for Ryanair to implement this system. Instead, it seems like the airline is willingly violating their customer's right to data protection in order to obtain an unfair competitive advantage over alternative booking channels," NOYB said in a statement.

NOYB has successfully launched privacy challenges against some of the world's largest multinational companies across the European Union under the bloc's General Data Protection Regulation (GDPR), introduced in 2018.

NOYB alleged that Ryanair's verification procedures are not valid under the GDPR because it does not provide comprehensible information about the purpose of the "intrusive process." (Reporting by Padraic Halpin, Editing by Louise Heavens)