* Government does not say why central bank governor detained
* Governor Rimsevics also sits on ECB Governing Council
* Finance minister urges Rimsevics to step down while being investigated (Adds quotes, details)
RIGA, Feb 18 (Reuters) - Latvia's anti-corruption agency has detained central bank governor Ilmars Rimsevics, prompting calls for him to step aside while he is under investigation.
In a statement to Reuters, Latvia's Prime Minister Maris Kucinskis did not say why Rimsevics, a member of the European Central Bank's Governing Council, had been detained or what he was being investigated for.
However, he attempted to reassure people that the economy was stable.
"There are no indications that would suggest threats to the financial system of Latvia," Kucinskis said in an emailed statement.
Finance Minister Dana Reizniece-Ozola said Rimsevics should step aside for the time being to protect the Baltic country's reputation.
"Given that the governor of the central bank is a symbol for every country, I think that it would be sensible at this moment that Mr. Rimsevics, at least during the investigation, steps down," Reizniece-Ozola told a news conference.
"Under the current circumstances... every day that Mr. Rimsevics remains in the post of governor of the central bank, the situation (for the reputation of Latvia's financial system) substantially worsens," she said.
Rimsevics' lawyer told local media that the detention was unlawful.
"A complaint is being prepared at the moment," the lawyer, Saulvedis Varpins, told news agency LETA without elaborating.
The Latvian central bank is an independent institution and Rimsevics has been its head since 2001. He has been a member of the ECB's Governing Council since January 2014, when Latvia adopted the euro.
A spokesperson for the European Central Bank declined to comment on Rimsevics' detention.
Latvia's Economics Minister Arvils Aseradens, speaking on Radio Latvia, also said the governor should consider resigning.
The home and office of the central bank's governor were searched on Friday, the state broadcaster said on Saturday.
It is a another setback for Latvia's banking sector, which has also been hit by allegations by the U.S. Treasury Department's Financial Crimes Enforcement Network that its third largest financial institution by assets, ABLV Bank, has institutionalised money laundering.
FinCen said last week that it was seeking to impose sanctions on ABLV. ABLV said in a statement in response on Tuesday that FinCen had referred to unfounded and misleading information about the bank. (Reporting by Gederts Gelzis, writing by Johan Ahlander; Editing by Toby Chopra and Susan Fenton)