The government has barred the central bank chief, Ilmars Rimsevics, from leaving his country over accusations that he solicited a bribe. Unable to travel, he could not attend an ECB policy meeting in Frankfurt on Thursday.
The ECB is now asking the European Court of Justice if the restrictions imposed on Rimsevics comply with the bank's rules, which say governors can only be relieved of office if they can't fulfill their duties or are "guilty of serious misconduct".
"The Governing Council has decided, again unanimously, to ask for clarification ... whether individual security measures imposed on the governor of Latvia's bank ... have had the effect of relieving him from office and if these measures comply with (EU) law," ECB President Mario Draghi told a news conference on Thursday.
Rimsevics, who denies all charges, is one of three members of the ECB policy-making Governing Council currently under investigation, in what some inside the institution perceive as a threat to its independence.
He was detained by anti-corruption agents last month, suspected of taking a bribe. He has refused to resign, creating a political dilemma for the Latvian government, which cannot sack him, and an embarrassment for the ECB.
The Latvian central bank has stripped him of his salary and barred him from accessing documents.
The ECB's Governing Council is made up of six Executive Board members, who run the institution and include Draghi, and the chiefs of the euro zone's 19 national central banks.
The Bank of Latvia was represented by Deputy Governor Zoja Razmusa at Thursday's meeting.
The other two ECB governors under investigation in their own countries, Greece's Yanis Stournaras and Slovenia's Bostjan Jazbec, regularly take part in meetings.
(Additional reporting by Gederts Gelzis in Riga; editing by Larry King)
By Francesco Canepa