Officers at the large immigration detention camp located at the Fort Bliss army base in Texas are allegedly mistreating detainees, with accusations including beatings, sexual abuse and clandestine deportations of non-Mexican nationals into Mexico, according to a coalition of local and national US civil rights organizations.

In a 19-page letter, addressed to senior government officials at the Immigration and Customs Enforcement (ICE) agency and Fort Bliss military command, the coalition accuses officers at the immigration detention facility on the base, called Camp East Montana, of being “in violation of agency policies and standards, as well as statutory and constitutional protections”.

The advocates called for the immediate closure of the camp, where more than 2,700 detainees are being held in a complex of tents.

“In light of these abuses, we urge the end to detention of immigrants at Fort Bliss,” said the letter signed by eight organizations, including the American Civil Liberties Union, Humans Rights Watch, Estrella del Paso, the Texas Civil Rights Project and Las Americas Immigrant Advocacy Center.