American Airlines has apologized to a wounded vet after preventing his award-winning service dog to board with him on a flight Sunday.

Captain Jason Haag, a former Marine who served tours in Iraq and Afghanistan, was attending a gala for Service Dog of the Year in Los Angeles where his German shepherd, Axel, was awarded the top honor. 

The veteran, who suffers from post-traumatic stress disorder (PTSD) and is a recovering alcoholic, was paired with the dog in 2012 through K9s for Warriors, a group that connects disabled veterans with service dogs.

Haag and his wife were scheduled to fly home to Fredericksburg, Va. after the event but as they were boarding, an American Airlines gate agent reportedly pulled him out of the line, told the veteran the flight was full and demanded proof that Axel was a real service dog, reports First Coast News.

“Well I answered all their questioned but didn't provide "paperwork" because 1) it's illegal to ask for and against federal law 2) I don't carry it because I've never had issue 3) I called ahead and everything was fine 4) but I did provide an ID to try and appease them. But to no avail,” Haag posted on his Facebook page.

Well ladies and gentlemen we have been denied access and not been allowed to board our plane by American Airlines due to...

Posted by Jason and Axel on Sunday, September 20, 2015

The Marine also said that he and his wife had been waiting in the gate area for two hours with their dog and were never question ahead of time. 

Axel was wearing a special service dog vest and harness – which is in compliance with the airline’s existing policy regarding service animals-- but an airline employee continued to interrogate Haag about his disability and demanded documentation.

Haag continued, “They had my wife in tears in front of 200 people as they brought more managers over to try and bully us.”

Staff members with the American Humane Association re-booked the couple’s flights, and a hotel room for the extra night in Los Angeles.

American Airlines issued Haag an apology Monday, reports ABC. 

"We apologize to both Captain Haag and his family for the confusion with the travel plans, yesterday. Thank you, Captain Haag, for your service to your country. We are extremely proud to fly you, Axel and your family," American Airlines spokeswoman Victoria Lupica.

But the American Humane Association says Haag’s experience highlights the need for better employee training.

"Service animals are absolutely essential to so many people who struggle with emotional and physical challenges," said Dr. Robin Ganzert, president and CEO of American Humane Association in a release. "In this case, the airline did not even follow its own guidelines. We call upon the company to reimburse the costs endured by Captain Haag in the course of this regrettable action, and on all airlines to better train their staff."