Mexican immigration authorities deported on Thursday 22 US adults who were being treated in the two centres close to the coastal town of Ensenada near the border with California. 

Another 55 minors from the centres were handed over to US consulate authorities to be returned to their parents.

"In two cells we found closed-circuit television, handcuffs and blood stains," Francisco Javier Reynoso, head of the National Immigration Institute in the state of Baja California, told a news conference. 

"For us all this is sufficient to start an in depth investigation, to arrest the guilty and to start legal proceedings against them in Mexico because they lacked legal permits to operate in the country," Reynoso said. 

Anonymous complaints

One US citizen has been arrested in connection with the closures and another is fugitive, Reynoso said.

The two centres - which authorities said were charging up to $5,000 per month for treatment - were raided after anonymous complaints of physical and psychological maltreatment and the use of medicines that had expired. 

In September, authorities closed down three other rehabilitation centres in the same area of northern Mexico and deported 590 US teenagers who had been sent to them for treatment of drug, alcohol or behaviour problems.

Those centres were shut down after patients complained of abuse.