Air Italy has become the first airline in Europe to introduce non-binary gender options for travelers who don't define themselves as male or female.

The Italian carrier follows United Airlines, which became the first U.S. airline to add a third option, "X" or unspecified, in the gender category for LGBTQ travelers.

Last year, the International Air Transport Association approved changes to booking procedures to include non-binary gender options.

When booking a flight with Air Italy, passengers can now check the prefix "Mx" instead of male or female.

The carrier is also working with LGBT group Arcigay on other inclusivity initiatives.

"The decision of a first-tier airline like Air Italy to invest resources and time to focus on inclusivity, is a positive example that we hope is followed by others," said Gabriele Piazzoni, General Secretary of Arcigay in a statement.

"The civil progress of a country depends not only on its laws, but also by the way in which the private sector puts in place anti-discrimination initiatives that take into consideration the many differences that exist."