Americans will be able to choose a gender neutral "X" on passport applications, instead of male or female, starting April 11, the US government announced Thursday.

This means that Americans identifying as transgender will be able to choose "X" on applications, regardless of the gender shown on their birth certificates or other previous official documents.

"For far too long, transgender, non-binary, and gender non-conforming Americans have faced significant barriers to travelling safely and many have not had their gender identity respected as they travel within the United States and around the world," the White House said.

"This is a major step in delivering on the president's commitment to expand access to accurate identification documents for transgender and non-binary Americans," a statement said.

The White House also said that the TSA, which runs security at airports, "is working closely with air carriers across the nation to promote the use and acceptance of the 'X' gender marker to ensure more efficient and accurate passenger processing."

Two major domestic airlines already offer a "third gender marker option" for travelers making reservations and another will join them later this year, the White House said.

The TSA has also changed procedures in order to "remove gender considerations when validating a traveler’s identification at airport security checkpoints."