Chile's militarized national police, the Carabineros, on Friday defended the legitimacy of its actions during an operation last September targeting militant Mapuche Indian leaders in the country's south.

Gen. Gonzalo Blu, head of that institution's Intelligence Directorate, made the remarks at a press conference a day after the Attorney General's Office said police may have tampered with evidence as part of Operation Hurricane.

"Our investigation has been and remains in accordance with existing law," Blu said. The AG's office is "calling into question the decisions made and jurisdictional control exercised on that occasion," the general said.

The government has ordered the Carabineros to conduct an internal investigation to shed light on its actions during the operation.

Besides denouncing irregularities in the case, the AG's office announced its decision to halt Operation Hurricane, although acting Interior Minister Mahmud Aleuy said a strong police presence would be maintained in the southern region of Araucania.

Defense attorneys for the Mapuches, meanwhile, announced that they will ask for the complete dismissal of a case against eight suspects who were arrested in September for alleged terrorist acts, including the torching of dozens of trucks.

Those suspects were subsequently released from custody.

Among other evidence in the case, police presented WhatsApp messages that appeared to show the suspects had coordinated the attacks.

But the AG's office says those conversations were allegedly "planted" on the Mapuche leaders' cellphones.

Referring to the phones confiscated from the suspects, Blu said Friday that the Carabineros had acted under the orders and supervision of the Prosecutor's Office for High-Complexity Crimes and the AG's office's specialized unit for the investigation of money laundering, economic crimes and organized crime.

"I'm very surprised at the public declaration not to continue to pursue the case, (a decision that comes) after a prosecutor in Araucania filed a complaint over evidence that we put at his disposal," Blu said.

Mapuche militants are seeking to reclaim lands lost during a late-19th-century "pacification" campaign against the indigenous people of southern Chile.

Mapuche Indians make up around 650,000 of Chile's 17 million people and are concentrated in Araucania and greater Santiago.