A manager of the Exmo Bitcoin exchange has been kidnapped in Ukraine.
According to Russian and Ukrainian media reports Pavel Lerner, 40, was kidnapped while leaving his office in Kiev's Obolon district on 26 December.
The reports said he was dragged into a black Mercedes-Benz by men wearing balaclavas.
Police in Kiev confirmed to the BBC that a man had been kidnapped on the day in question, but would not confirm his identity.
Mr Lerner is a prominent Russian blockchain expert and the news of his kidnapping has stunned many in the international cryptocurrency community.
Exmo described him as an analytics manager.
Blockchain is the technology that underpins the digital currency Bitcoin.
Exmo Finance is registered with Companies House in the UK, but has its main operations in Ukraine.
According to its website, it has 94,955 active users trading cryptocurrencies.