Three men were arrested in the UK in connection with the €13 million cyber-heist at Bank of Valletta in February last year, a statement by the UK’s National Crime Agency. 

Hackers accessed the bank’s systems and moved the money into foreign accounts before spending part of the money on high-end goods including Rolex watches and an Audi A5 car. 

David Cunningham, the National Crime Agency's Belfast branch commander said the investigation focused on "a number of individuals we suspect may have been involved in laundering money on behalf of the organised crime group who carried out the cyber-attack."

The investigation in the UK had the assistance of the Malta Police Force's economic crimes unit.

On Wednesday two men aged 22 and 17 were arrested in raids in West Hampstead and Ladbroke Grove in London. A third man was interviewed under caution. 

On Thursday the Police Service of Northern Ireland arrested a 39-year-old man in Belfast on suspicion of money laundering offences, fraud and theft. He remains in custody.

The investigation revealed that a strain of malware was used to access systems and illegally remove the funds into UK accounts. 

Around £800,000 (€950,000) was transferred into accounts in London and Belfast and in the following hours a number of card payments and cash withdrawals totalling £340,000 were made before a block could be put on them.

"They included payments to high end stores such as Harrods and Selfridges in London, around £110,000 spent on Rolex watches at a store in London, and payments for a Jaguar and Audi A5 from a car dealership," the National Crime Agency said in a statement.

Officers are still seeking a number of other suspects in connection with their investigation, the NCA said.

In May, Bank of Valletta said it had recovered €10 million of the €13 million stolen.