UK police have been involved for months in the case of a British man arrested in Germany on suspicion of spying for Russia, the Met boss has said.
The 57-year-old man, named only as David S, worked at the British embassy in Berlin and was detained on Tuesday.
He is alleged to have passed documents to Russian intelligence for money.
Metropolitan Police commissioner Dame Cressida Dick said police had been working closely with German authorities and the UK government over the issue.
She told LBC Radio: “I think it’s a very good example of international co-working.”
MI5 and other UK agencies had been working alongside bodies including the BKA – Germany’s federal criminal police office – and prosecutors ahead of the arrest in Potsdam, outside Berlin.
The man’s home and workplace have been searched and he appeared before a judge on Wednesday. He was ordered to remain under arrest pending further inquiries.
Dame Cressida said: “If this person is charged, we will support any trial, wherever that may be.
“At the moment the Germans are most certainly handling it.”
She added of the arrest that “these things are, thankfully, very rare”.
The arrest of a security guard at the British Embassy in Berlin is a reminder that old-fashioned spying has not gone out of fashion.
Stories of betrayal, bribes and stolen documents make for racy tales with all the elements of spy fiction.
But the truth is that nothing in the Berlin case should surprise us. What is alleged to have happened is not very unusual, even if we do not hear about it very often.
In recent years, Western states have called out Russia for the aggressive actions of its intelligence services – for instance the GRU, Russian military intelligence, using nerve agent in Salisbury or blowing up an arms depot in the Czech Republic, both actions killing innocent people.
But you will not hear the same complaints when it comes to the allegation involving the British Embassy in Berlin.
That is because if it turns out to be true, following the legal process, then it would be business as usual when it comes to more traditional spying.