According to Navalny, Russian state prosecutor Yuri Chaika and criminal gangs linked to him used an unnamed Latvian bank to launder millions of dollars.
Spektr quotes Elina Avotina, spokewoman for the Latvian financial regulator, the Financial and Capital Markets Commission (FKTK) saying the regulator will look into the allegations.
The news is just the latest in a long line of concerns about the use of Latvian banks to launder vast sums of money from Russia and other countries to the east.
Often combined with complex offshore schemes using companies in various jurisdictions, Latvian banks have become adept at catering for 'Non-Resident' clients.
Latvian banks have been named in connection with multi-billion dollar scams in Moldova and Russia.
Another recent case centering on the role of Latvian banks in the United Kingdom's courts involved parties from the United Arab Emirates and Georgia and in the resulting judgment numerous doubts were raised about the role of the banks in making money disappear.
You can read more in English about the shocking Chaika case HERE.