An unspecified cybersecurity incident is impacting Transport for London (TfL), the government body responsible for the transport network in Britain’s capital, it announced late on Monday.

In a statement on its website, TfL said: “We are currently dealing with an ongoing cyber security incident. At present, there is no evidence that any customer data has been compromised and there has been no impact on TfL services.”

According to BBC News, staff have been asked to work from home if possible. The incident has principally affected “backroom systems” at TfL’s corporate headquarters, the BBC added.

The TfL statement added: “The security of our systems and customer data is very important to us, and we have taken immediate action to prevent any further access to our systems.”

A spokesperson for Britain’s National Cyber Security Centre said the agency was working with TfL alongside law enforcement to fully understand the impact of the incident.

TfL said it would provide a further update when the incident has been resolved.