MEXICO CITY (Reuters) -Mexico's banking regulator slapped three financial institutions, which had been sanctioned by the U.S. for alleged money laundering, with more than 185 million pesos ($9.81 million) in fines in June, local media reported on Tuesday.

The U.S. Treasury last month prohibited certain transactions with Mexico's CIBanco, Intercam Banco and Vector Casa de Bolsa as part of fentanyl sanctions.

The fines were largely related to money-laundering prevention, local media reported, citing data published by the regulator. Reuters was not immediately able to access the data on the regulator's website.

Intercam faced the largest amount in fines, more than 92 million pesos, while CIBanco received upward of 66 million pesos and Vector will need to pay more than 26 million pesos, according to the reports.

All three have previously denied the allegations from the U.S. In late June, the banking regulator stepped in to manage the three firms.

Mexico's government has also rebuffed the allegations, saying the Treasury had not provided Mexico with proof to back up its claims.

($1 = 18.8499 Mexican pesos)