Suspected spies for Russia held in major UK security investigation

Three suspected spies for Russia in the UK have been arrested and charged in a major national security investigation, the BBC can reveal.

The defendants, all Bulgarian nationals, were held in February and have been remanded in custody since.

It is alleged they were working for the Russian security services.

They are charged with possessing identity documents with "improper intention", and are alleged to have had these knowing they were fake.