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Bitcoin: MtGox exchange goes offline

25 February 2014 Last updated at 23:12 GMT

Bitcoin, a virtual currency which only exists on the internet, has become increasingly attractive as it does not involve exchanging currencies.

However, it has seen a sharp fall in its value after one of the biggest online exchanges, MtGox, unexpectedly shut down, owing hundreds of millions of pounds and prompting the sharp fall in the value of the currency.

Robert Peston reports.