Facebook has started charging users money - to send messages to celebrities or people they don't know.

The fee is being introduced in Britain after a successful trial in the United States.

You'll be asked to pay by credit or debit cards when you run up bills by messaging people outside your social network.

The standard charge will be around 70 pence sterling, or nearly 60 cent - but to grab the attention of a celebrity it will cost more - in some cases just over ten pounds, or 12 euro.

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It marks a significant change for the social network, which has always boasted of being 'free'.