Refugio Ruiz, File, Associated Press
FILE - In this May 22, 2015, file photo, Mexican state police stand guard near the entrance of Rancho del Sol, where a shootout with the authorities and suspected criminals happened near Vista Hermosa, Mexico. Mexico's National Human Rights Commission said on Thursday, Aug. 18, 2016, that it has concluded that 22 people were arbitrarily executed by federal police during the event. Commission President Luis Raul Gonzalez Perez said their investigation revealed a range of human rights abuses on the part of government forces.

MEXICO CITY — Federal police executed at least 22 people on a ranch last year, then moved bodies and planted guns to corroborate the official account that the deaths happened in a gunbattle, Mexico's human rights commission said Thursday.

One police officer was killed in the confrontation in the western state of Michoacan on May 22, 2015. The government has said the dead were drug cartel suspects who were hiding out on the ranch in Tanhuato, near the border with Jalisco state.

The National Human Rights Commission said there were also two cases of torture and four more deaths caused by excessive force. It said it could not establish satisfactorily the circumstances of 15 other deaths.

"The investigation confirmed facts that show grave human rights violations attributable to public servants of the federal police," commission President Luis Raul Gonzalez Perez said.

Mexico's national security commissioner, Renato Sales, who oversees the federal police, denied the accusations, holding his own news conference before the rights commission had finished its own.

Sales said federal police ordered the suspects to drop their weapons and surrender, but were answered with gunfire.

"The use of weapons was necessary and proportional against the real and imminent and unlawful aggression," Sales said. "That is to say, in our minds they acted in legitimate defense."

The lopsided death toll had led to suspicions that officers might have arbitrarily killed people during the operation.

The rights commission questioned the government's explanation of what led to the clash in the first place.

Federal police had said they encountered a truck and took fire from its passengers before being led to the ranch.

The commission's report said the government did not produce evidence supporting that account and it said witness statements suggested 41 federal police had sneaked onto the ranch as early as 6 a.m. Officers started their assault at least an hour earlier than they maintained in reporting on the incident, the commission said.

The commission's investigation found that 40 of the civilians killed were shot. One died in a fire and another was run over.

The government refused to release autopsy reports on those killed.

The government's transparency watchdog earlier said there was no evidence to indicate human rights violations.