The Foreign Office spokesman said: "We cannot comment further on the nature of the threat at this time."
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David Cameron is to put working people "front and centre" of his economic plan our economic plan" if the Conservatives win the election.
Nearly 38,000 runners will hope to complete Sunday's London Marathon making it the biggest event in its 35-year history.
Rain across central Britain with longer, intense downpours with thunder in places this evening. A lucky few will stay sunny and dry.