German magazine Spiegel said David Cameron has warned German Chancellor Angela Merkel he may have to bring the UK referendum on EU membership forward if Jean-Claude Juncker becomes the European Commission chief.
The Prime Minister said he sees Mr Jucker, Mrs Merkel's candidate for the post, as too federalist and likely to damage his hopes of reforming Britain's EU ties.
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Spain and Portugal have seen an increase in bookings from British holidaymakers amid fears of terror attacks at other locations.
French labour strikes are threatening to bring the country to a standstill by blockading fuel supplies.
David Cameron has described the Institute of Fiscal Studies as a 'gold standard' group of experts, as it warned of 'Brexit' dangers.