The head of Latvia's central bank, Ilmars Rimsevics, was detained by the country's anti-corruption agency on Sunday, reports BBC.
His home and offices at the Bank of Latvia were both raided by officers.
The country's Corruption Prevention Bureau gave no details about its investigation, or the nature of the raids.
Latvia's Prime Minister, Maris Kucinskis, has called an emergency cabinet meeting today (Monday) but added there was no apparent national threat.
"There are no signs that there is any threat to the Latvian financial system," he said in a statement.
He said neither he, as prime minister, nor any other officials had any reason to interfere with the anti-corruption agency's work.
"The institution works professionally and accurately," he said, pledging the government's full support and saying there would be no outside influence.
The Bank of Latvia said it could not comment on the investigation, but said it had a "zero tolerance policy in respect of corruption and other illicit activities".
It said the bank's operations were unaffected by the investigation, and that it would open on Monday as usual.
A number of banks in Latvia have been subject to investigations in recent months.
In July 2017, two banks were fined for allowing their clients to circumvent international sanctions preventing payments to North Korea.
Another, Norvik Bank, is embroiled in a dispute with the state over what it calls "unfair, arbitrary, improperly motivated and unreasonable regulatory treatment".
Precisely what that entails has not been disclosed.
