It’s a small portion of what the US gives Mexico each year but conveys a pointed message to its southern neighbour, which has come under the spotlight for abuses including last year’s disappearance of 43 students at the hands of police.

The State Department is obliged by law to hold back 15% of some anti-drug aid to Mexico under the Merida Initiative until it delivers a report to Congress on human rights in the country, and spokesman Mark Toner said the department has not sent the report.

“This year the Department was unable to confirm and report to Congress that Mexico fully met all of the criteria in the fiscal year 2014 appropriation legislation, and the 15 percent was redirected away from Mexico,” Toner said.

He said that Washington continues to support Mexico’s efforts to reform its law enforcement and justice systems, and added that Mexico and the United States “have made significant progress” working to combat organized crime.

In a statement, Mexico’s Foreign Relations Department said the country is aware it has challenges and is committed to protecting human rights.

“Nevertheless, it rejects any kind of unilateral practice that judges the human rights situation in a country,” the statement said.

Washington sent Mexico $195m under the Merida Initiative last year, according to State Department figures.

The $5 million in diverted funds will go instead to Peru for efforts to eradicate plantations of coca, the source of the base ingredient for cocaine.