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Spain-Gibraltar row: A quick guide to the history

5 August 2013 Last updated at 23:58 BST

The Prime Minister says he has "serious concerns" over Spanish proposals to charge a fee for crossing the border into Gibraltar.

Spain has said it is considering a range of proposals including a new 50 euro (£43) fee to cross the border into the British territory.

But what's the background to the escalating tensions?

Tom Burridge explains.

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