Gaponenko has been detained in connection with a criminal process based upon possible anti-Latvian activities, his attorney Imma Jansone told the LETA newswire.
She also said that Gaponenko claimed to have gone on a hunger strike as a form of protest against the Latvian security services.
As previously reported, the Latvian Security Police has detained Gaponenko, a well-known Russian nationalist radical and the leader of an unregistered organization, the Congress of Non-citizens, over possible anti-Latvian activities, according to LETA's sources.
The Security Police did not identify the detainee at the time by the name but told LETA that a person had been detained as part of the criminal proceeding opened on April 4 for activities targeting Latvia's independence, sovereignty, territorial integrity and state power in an anti-Constitutional manner.
Searches are being conducted at locations related to the detainee. The Security Police would not give any detailed information, saying it did not want to undermine an ongoing investigation.
The Security Police said that the detainee is already facing criminal charges for instigation of ethnic hatred under a different criminal proceeding. LETA already reported that in February 2017 the prosecutor's office sent to the court a criminal case in which Gaponenko has been charged with instigation of ethnic hatred against Latvians, Lithuanians and Estonians via a Facebook post. The court will start hearing the case on June 19.
In the latest incident involving Gaponenko, Latvian MP Ainars Latkovskis (Unity party), the chairman of the parliament committee on defense, interior affairs and corruption prevention, asked the Security Police to probe a recent but by no means uncharacteristic Facebook post by Gaponenko about Americans planning to carry out ethnic cleansing in Riga.
Gaponenko wrote on his Facebook account that he had received information from an ''American friend'', who had said that NATO would hold a vast military exercise in Latvia in May, during which American soldiers disguised as Russian-speakers (having presumably mastered the language in advance) will attempt to instigate disorder and pin the resulting strife on Russia.
Gaponenko claimed that the Americans, together with the Latvian Security Police, will be carrying out arrests of Russian speakers to put them in concentration camps or to execute them, in a familiar, if by now cliched, fantasy of perpetual victimization.
However, according LETA's sources, Gaponenko's detention yesterday is not related to this particular Facebook post.