The mayor of Portugal's capital, Lisbon, has come under fire after admitting that officials handed over the personal data of organisers of an anti-Kremlin demonstration to the Russian embassy in Lisbon.
They include Russian activist, Pavel Eliazarov, who has submitted a formal complaint to the authorities.
The activists arranged a protest outside the Russian embassy in Lisbon in support of detained Russian dissident Alexei Navalny in January.
Eliazarov said: "As a refugee, I felt protected by the Portuguese State. I even had international protection. For example, when I travel, I know that if anything happens, if they put my name on the Interpol list, Portugal will protect me. And at the same time, they send my personal data, like my address to Russia. I feel less secure, now."
Lisbon Mayor Fernando Medina apologised for what he said was an “unfortunate mistake” which he blamed on the municipal chamber's workers.
Lisbon Mayor: 'Mistake due to bureaucracy'
"The mistake was due to the bureaucracy of the services that applied to this protest the same protocols as for scores of other protests that take place in the municipality,'' Medina said.
Under Portuguese law the organisers of such protests must provide the local authorities with their personal details, including address and contact information.
In a statement, his office acknowledged the breach of data protection rules but said that it `"vehemently rejects any accusations and insinuations of complicity with the Russian regime.''
The latest development comes at a sensitive time for the opposition to Russian President Vladimir Putin.
Navalny, Putin's most ardent political foe, was arrested in January and given a 2 1/2-year prison term for violating the terms of a past sentence for embezzlement; which he dismissed as politically motivated.
It is not the first time concerns have been raised over data being misused. Other campaign groups, including a group supporting Palestinians, had criticised the Lisbon municipal chamber in the past for also sharing potentially sensitive data ahead of previous protests.