United Airlines has found itself once again embroiled in a customer service scandal after newly released video shows an employee pushing a 71-year-old passenger to the floor.

The confrontation took place during an argument over a ticket at George Bush Intercontinental Airport in Houston on July 21, 2015.

Footage of the incident emerged Wednesday, a week after passenger Ronald Tigner filed a lawsuit against the US carrier and two of its employees.

According to the lawsuit, Mr Tigner was attempting to get a new ticket printed after his boarding pass was deemed illegible when two United employees, Alejandro Anastasia and Ianthe Phillips-Allred refused to help, with Mr Anastasia eventually pushing him.

Watch a video of the United Airlines incident below:

https://www.youtube.com/watch?v=_QeJ40o0IDs

Mr Tigner claimed the pair was laughing and cursing at him, and he was left motionless on the terminal floor for 50 seconds before a fellow passenger offered assistance.

He suing the two employees for more than $US1 million ($A1.32 million), alleging negligence.

Mr Tigner’s attorney, William Hoke, told Houston television station when his client asked Mr Anastasia for a new copy he grinned and said: “Can’t you see I’m busy?”

The 71-year-old responded by telling him to “wipe that smile off your face,” to which Mr Anastasia reacted aggressively, swearing and “suddenly, unexpectedly and violently injured” Mr Tigner.

The lawsuit states the incident caused “severe personal injuries and damages” which resulted in medical expenses and a loss of wages.

United released a statement in response to the video, saying Mr Anastasia’s behaviour was “completely unacceptable”.

“The actions shown here do not reflect our core values or our commitment to treat all of our customers with respect and dignity,” the statement read.

“We are reviewing all circumstances surrounding this incident and reaching out to our customer through his attorney to profusely apologise for what occurred and to make this right.”

A bad year for United

United Airlines has been the focus of controversy in recent months, after passenger David Dao was forcibly removed from his flight.

Mr Dao refused to give up his seat on an overbooked flight, and was dragged off bloodied by airport security.

Mr Dao suffered a concussion, broken nose and two missing teeth, along with other injuries.

In May, a man was detained by police after a United Airlines flight attendant reported him for placing his hand on his own son’s knee.