MEXICO CITY — Federal police killed 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 others who were shot to death.

“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 against suspected members of the Jalisco New Generation cartel.