Ten people who spied for Moscow in the US have arrived in Russia after being deported as part of the the biggest spy swap since the Cold War. They were driven away from a Moscow airport in a convoy of vehicles hours after the exchange in Vienna, Austria. Four Russians freed by the Kremlin in exchange were collected by a US plane at Vienna airport. The American jet flew to an air base in the UK before continuing on to an undisclosed destination. Washington said the spy swap had been completed successfully. Without mentioning the actual swap, Russia said the 10 people freed by the US had been released "for humanitarian considerations", and it noted "the general improvement of Russia-US relations". The exposure of the deep-cover Russian spying ring last month had raised questions about how genuine was the Kremlin's commitment to good relations with the White House - the Obama administration's so-called "reset". In another development, the UK's Home Office said it was urgently reviewing whether to deprive one of the Russian spies, Anna Chapman, of her British passport. She has the passport because of her previous marriage to a Briton.