In a brief statement released in London on October 10, Moody's said:
"Moody's has today withdrawn Trasta Komercbanka's standalone bank financial strength rating (BFSR) of E+, equivalent to a b3 baseline credit assessment (BCA), and the long and short-term deposit ratings of B3/NP."
"Moody's has withdrawn the rating for its own business reasons," the agency said without adding any further details other than noting that the bank is based in Riga and reported total assets of €480 million at end-June 2014.
Trasta specialises in providing services for wealthy individuals and businesses, many of them from Russia and the CIS countries and as a result is classed as one of Latvia's specialist "non-resident" banks.
There was no immediate response from the bank to Moody's announcement.
As reported previously by LSM, Trasta was recently named by investigative journalism group OCCRP as part of a massive $20bn money laundering scheme, though there is no indication the Moody's decision is linked to the claim.
In a separate move on October 10 the national financial regulator the Financial and Capital Markets Commission (FKTK) issued a warning to another non-resident bank, Rietumu Banka, over "weaknesses identified in its credit risk assessment with clients," which FKTK said posed "a significant reputational risk."
FKTK said it had "issued a warning to the bank, thereby encouraging market participants to avoid similar violations in the future."
Some analysts and organizations including the International Monetary Fund have expressed reservations about the relatively large size of Latvia's non-resident deposit banking sector.
However, government, regulators and the Latvian central bank insist the sector is constantly monitored and poses no threat to the country's economic stability.