United Kingdom's Foreign Office was the target of a serious cybersecurity incident earlier this year, according to tender documents posted on the government's website.

"The Authority was the target of a serious cyber security incident, details of which cannot be disclosed," according to the document. The news was first reported by The Stack.

The Foreign and Commonwealth Office was forced to call in BAE Systems Applied Intelligence to deal with the incident, according to the documents. It paid BAE Systems 467,326 pounds ($632,946) for the work.

The Foreign Office did not immediately respond to a request seeking comment.

It was not immediately clear who was responsible for the cyberattack – or the effects of it. It was also unclear why the details of the incident could not be disclosed.