It was swearing - not kissing - that got a lesbian actress and her girlfriend escorted off a plane as it sat at a Texas airport, Southwest Airlines say.

The airline said the couple became profane after being reprimanded for what actress Leisha Hailey characterised as "one modest kiss".

Hailey immediately used her Twitter account to accuse the airline of discrimination and call for a boycott.

Hailey is best known for playing Alice Pieszecki in the now defunct Showtime lesbian life drama The L-Word.

The incident cast a national media spotlight on the actress, who is now part of the electro-pop duo Uh Huh Her.

Halley's publicist Libby Coffey said the encounter was real and was "absolutely not" done as a publicity stunt for her band's upcoming breast cancer awareness tour.

Hailey and partner Camila Grey also denied in a statement on Tuesday that the affection they showed toward each other was inappropriate.

"We want to make it clear we were not making out or creating any kind of spectacle of ourselves, it was one modest kiss," the written statement said.

"We are responsible adult women who walk through the world with dignity. We were simply being affectionate like any normal couple."

The airline responded that Hailey's display of affection was excessive and drew customer complaints, and that the women cursed after being reprimanded.

"Additional reports from our employees and customers onboard Flight 2274 during a stop in El Paso on Sunday now confirm profane language was being used loudly by two passengers," the airline said.

"Although we have reports of what customers characterise as an excessive public display of affection, ultimately their aggressive reaction led to their removal from the aircraft."

Hailey and Grey acknowledged that they became upset after the flight attendant reprimanded them and told them Southwest is a family airline.