Sindri Þór Stefánsson was arrested earlier this year and imprisoned at a low-security prison less than 100 kilometres from Keflavik International Airport on Iceland.
But he escaped and is believed to have used a fake passport to board a commercial flight to Stockholm's Arlanda Airport – the same plane carrying Icelandic Prime Minister Katrín Jakobsdóttir, who was on her way to a summit with Indian PM Narendra Modi in Sweden on Tuesday.
Stefánsson was still at large on Wednesday afternoon, reports Icelandic news site Visir.
“We have been informed by Icelandic police that a detained man has escaped and is suspected of having made it to Sweden. The man has not been detained in Sweden,” said Swedish national police spokesman Stefan Dangardt in a statement.
Stefánsson was one of around a dozen people arrested earlier this year, suspected of having stolen hundreds of computers from data centres across Iceland in what has been dubbed the “Big Bitcoin Heist”.
The machines are worth around $2 million and can be used to create digital currencies.
File photo of a data centre in Iceland. Photo: AP Photos/Egill Bjarnason