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London is accumulating nicknames.

After the shocking, deadly 7/7 terrorist attacks on the subways and a bus, it was "Londonistan."

The British capital, some here feared, had become a center for Islamic extremists.

And now, after the dramatic poisoning of a former KGB spy — "Londongrad."

We have long known London to be a magnet for Russian dissidents and billionaires. But so far, the city's been spared any violent fallout from their turf wars or political fights. Maybe, no longer.

A British newspaper last week reported, citing unnamed U.K. government sources, that Britain is infiltrated with Russian spies — more so than it was even during the Cold War. This fact, the paper called, is a threat to the United Kingdom.

But that's something for the security services and government officials here to work out. What's given the average Brit a terrible jolt is this significant trail of radioactive poison, Polonium 210, that has been left in public places — airplanes, hotel bars, popular sushi restaurants and even a soccer stadium. While the health authorities here have given assurances that there is no greater public health danger associated with the poisoning of Alexander Litvinenko, you hear stories of people wracked with the jitters — scared to get on planes or go for sushi.

And the darker, deeper fear, only ever voiced in hushed tones ... Who else might possibly be able to get their hands on such a toxic substance?

Again, of course too, the issue of Great Britain, with its wide open doors, and generous offers of asylum to those who face persecution in their own countries, now possibly becoming a battleground for foreign political struggles.

Of course, speculation and accusation aside, the Litvinenko case is wide open. No one knows who killed this man, who spoke out about the abuses of the Russian security services at home in Chechnya. I will leave all those theories for now.

Currently, we have Litvinenko, finally laid to rest in a reinforced, hermetically sealed coffin in London's historic Highgate cemetery, where, incidentally, Karl Marx is also interred. His widow has tested positive for having reportedly minute quantities of polonium 210 in her system. Litvinenko's Italian contact, Mario Scaramella, a nuclear materials and espionage expert, the man who met Litvinenko at the Itsu sushi bar on Picadilly the day he fell ill, also tested positive, with significant quantities of the toxin in his system. Andrei Lugovoi and Dmitri Kovtun, two Russian businessmen who had drinks with Litvinenko after lunch, at the Millenium Hotel, are also contaminated, and Kovtun is said now to be very ill in a Moscow hospital. And seven employees of the Millenium Hotel bar have tested positive for having polonium 210 in their system. Health officials have said that their short-term health is not in danger, and the chances of illness much later is small, but that is all we know. While a greater public health scare does in fact at this point seem not to be an issue, this is a serious situation.

The sign on the boarded up Picadilly Itsu reads:

"A sad and strange espionage incident has turned this into a world famous meeting place."

We all have got caught up in John LeCarre — like the drama of this most fascinating story, it is in fact a brutal unsolved murder with a certain amount of psychological and physical fallout on an international scale. Many here in Britain have taken their hats off to Scotland Yard for tracing this radioactive trail so quickly and efficiently. The enormous presence of closed-circuit TV cameras in London will no doubt help them in their work going forward. However, there are also certain doubts that have speculated that much of their work remains to be done in Russia, whose guard is up, and who has set its own set of ground rules for the investigation. There may never be full resolution of this case — Let's hope that's not true.

Amy Kellogg is a London-based correspondent for FOX News Channel (FNC). She joined FNC in 1999 as a Moscow-based correspondent. You can read her complete bio here.

Amy Kellogg currently serves as a Senior Foreign Affairs Correspondent based in Milan. She joined Fox News Channel (FNC) in 1999 as a Moscow-based correspondent. Follow her on Twitter: @amykelloggfox