Criminal gangs are plotting a $1 billion (£618 million) cyber-heist on global financial institutions, Europol has warned, as they ratchet up the pressure on banks reeling from the record-breaking hit on JPMorgan Chase.

Secret listening on internet chatrooms by the European police investigative body has discovered planning by sophisticated Russian cyber-criminals aimed at pulling off one massive hit on a bank.

“We have intelligence and information about planning in this direction,” Troels Oerting, pictured, head of Europol’s European Cybercrime Centre in The Hague, said.

Bank insiders are being groomed, says Europol, to put in place programs that will override monitoring apparatus.

These insiders will close down alarm systems designed to alert staff when large amounts are unexpectedly transferred out of a bank.

“The criminals don’t want to make thousands of small thefts,” said Oerting. “Instead they want one big one on a financial institution.”