In an alert), information security firm Websense warned that the Popular's website 'has been compromised, and is infecting site visitors with malicious code.'

The attack, Websense said, creates a window within Popular's website that directs visitors to the hacker's website. It said it has since notified Popular of the attack.

Popular's marketing manager Lynn Lee on Monday confirmed the breach, and said it has since fixed the problem.

'No customer data has been lost,' she said.

Popular and the company that hosts its website in Hong Kong are both investigating the attack and will consider further legal action if it is able to identify the perpetrator.