Clarksons, the global provider of integrated shipping services, has confirmed it was subject to a cyber security incident involving unauthorised access to its computer systems.

In a statement on the London Stock Exchange, the company said its initial investigations found that unauthorised access was gained through a single and isolated user account which has now been disabled.

Clarksons assured clients and shareholders that it took immediate steps to respond to and manage the incident and that it has also put additional security measures in place to prevent a similar incident happening in the future.

However, it warned that the person or persons behind the incident may release some data today.

"Issues of cyber security 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," said chief executive Andi Case.

"As you would rightly expect, we're working closely with specialist police teams and data security experts to do all we can to best understand the incident and what we can do to protect our clients now and in the future.

"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."

London-based Clarksons said it has been working with the police as well as data security specialists to investigate the incident further and has notified the relevant regulatory bodies.

The company stressed that it takes issues of IT security "extremely seriously" and, as a result of the incident, it is continuing with a wider review of cyber security that began earlier this year.