Container shipping giant Clarksons announced on Wednesday that it fell victim to a cyberattack in which hackers made off with confidential company information.

The London-based shipbroker – one of the world’s largest shipping service providers – said the incident involved unauthorized access to its computer systems “via a single and isolated user account,” which has since been disabled.

The company warned the confidential data may be made public, after it refused to pay the ransom to hackers.

“Today, the person or persons behind the incident may release some data. As a responsible global business, Clarksons has been working with the police in relation to this incident. In addition, the data at issue is confidential and lawyers are on standby wherever needed to take all necessary steps to preserve the confidentiality in the information,” said the company in a statement.

Clarksons added that it took immediate steps to respond to and manage the incident, including putting additional security measures in place “to best prevent a similar incident happening in the future.”

The company said it’s working with data security specialists to investigate further, and has notified regulatory bodies.

Potentially affected clients and individuals are also in the process of being notified.

Andi Case, CEO of Clarksons, said in a statement (PDF): “Issues of cybersecurity are at the forefront of many business agendas in today’s digital and commercial landscape and, despite our extensive efforts we have suffered this criminal attack.”

“We hope that, in time, we can share the lessons learned with our clients to help stop them from becoming victims themselves. In the meantime, I hope our clients understand that we would not be held to ransom by criminals, and I would like to sincerely apologise for any concern this incident may have understandably raised,” Case said.

Earlier this year, container shipping company A.P. Moller-Maersk suffered a similar incident when a cyber-attack disrupted its operations.

Consequently, the company announced in its financial report an estimated $300 million in lost revenue.