Ransomware works by hackers targeting companies with malicious programs that can cripple systems overseeing everything from supply chains to payments to manufacturing, removing them only after receiving substantial payments.

Computer specialists and external cyber security experts had been working since New Year's Eve to isolate the virus, Travelex said last week, adding its branches were continuing to provide foreign exchange services manually.

The company is yet to ascertain what all data has been encrypted by the ransomware and said it was cooperating with Britain's National Crime Agency and the Metropolitan Police, who are conducting their own criminal investigations.

(Reporting by Juby Babu in Bengaluru; Editing by Shounak Dasgupta)