Australian Model Could Be Locked Up In US For Months

US immigration officials are sticking by their decision to arrest Australian model Adau Mornyang and keep her locked up for more than two months.

Mornyang, 25, was deemed "illegally present" in America after a judge in Los Angeles sentenced her to probation and community service in July for assaulting and interfering with a flight attendant on a "nightmare" Melbourne to Los Angeles United Airlines flight.

Mornyang's sister, Maria, claims the model had a valid visa and was in the US legally on September 17 when she was arrested in a "surprise ambush" by Immigration and Customs Enforcement officers who had revoked her visa without notice.

Mornyang remains in custody despite ICE deeming her "an expedited removal".

"Adau Mornyang is an illegally present Australian citizen who was processed as an expedited removal," ICE public affairs officer Rachael Yong Yow told AAP on Monday.