MEXICO CITY (Reuters) -The U.S. Treasury said on Wednesday it had extended a deadline to September 4 for a prohibition on certain transactions involving three Mexican financial institutions hit by sanctions last month over alleged money laundering linked to fentanyl trafficking.

The actions apply to Mexico's CiBanco, Intercam Banco and Vector Casa de Bolsa, which the Treasury said were identified as "primary money laundering concerns."

"This decision is the result of dialogue and collaboration between the Mexican government and U.S. financial authorities," Mexico's finance ministry said in a statement following the announcement.

Mexico had previously balked at the sanctions, arguing that they were unilaterally applied by the U.S. without providing Mexico with any evidence to back up the money laundering claims.

Since the sanctions were announced, Mexico temporarily took over the three financial firms to protect creditors and depositors.