Nearly 700 Revolut customers have been affected by a data breach which saw the fintech accidentally hand over passport details, bank account numbers and home addresses to cybercriminals posing as government officials. The payments group has contacted 680 people who it believes were affected by the scam after an initial investigation.

Revolut spent the weekend rushing to respond to the breach, which occurred after a hacker used a real government email that they had obtained to send a fraudulent request for private information. Revolut complied and handed over sensitive information including addresses, verification pictures, identity cards and Bitcoin activity. Hackers are threatening to release the information unless Revolut pays a ransom.

On Monday, the Information Commissioner's Office said it was investigating after Revolut reported itself. The incident underlines the increasing threat posed to businesses by cybercriminals. Since launching in 2015, Revolut has become Europe's biggest fintech with 80mn customers operating in 30 countries. It was recently valued at $115bn.

Mark Karpelès, former CEO of Mt Gox, was among those affected. He said Revolut should not have shared the information. A Revolut spokesperson said it identified a sophisticated external impersonation scam and immediately blocked the address.