EU referendum: Cameron warns UK exit could put peace at risk

Peace in Europe could be at risk if Britain votes to leave the European Union, David Cameron has warned.

The UK has regretted "turning its back" on Europe in the past, the PM said, arguing the European Union has "helped reconcile" countries and maintain peace.

Mr Cameron asked if leaving the union is a "risk worth taking".

Leave campaigners said Nato, not the EU, kept the UK safe and accused Downing Street of "losing the plot".

Vote Leave said: "During the renegotiation the PM said he 'ruled nothing out'. Now he thinks leaving the EU would lead to war. What changed?"

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Despite his security warning, Mr Cameron defended his decision to call the referendum, telling the BBC: "You shouldn't try to hold an independent sovereign nation in an organisation against its will."

There are just over six weeks to go until the 23 June referendum which will decide whether Britain remains in or leaves the EU.Later Boris Johnson, who wants the UK to leave the EU, will make a speech on the "cosmopolitan case for Brexit".

Mr Johnson - now free from his role as London mayor - will begin a battle bus tour of the country on behalf of the Leave campaign later this week.

The major speeches - from the most high-profile figures on both sides of the campaign - come as the referendum campaign intensifies, following last week's elections.

Mr Cameron, who was introduced by former Labour foreign secretary David Miliband, argued the EU - with Britain in it - had helped bring together countries that had been "at each others' throats for decades".

He warned the peace and stability Europe has enjoyed in recent years could not be guaranteed, saying leaving risked "the clock being turned back to an age of competing nationalism in EuropeWhile Europe has largely been at peace since 1945, Mr Cameron said it was barely two decades since the Bosnian war while, more recently, Russia has been at war with Georgia and Ukraine.

"Can we be so sure that peace and stability on our continent are assured beyond any shadow of doubt? Is that a risk worth taking? I would never be so rash as to make that assumption," he said.

Mr Cameron argued "isolationism has never served this country well"He ranked 2016 alongside other major events in European history, including the Spanish Armada in 1588, the battles of Blenheim and Waterloo in 1704 and 1815 respectively, the two world wars, as well as the fall of the Berlin Wall.

"The truth is this: what happens in our neighbourhood matters to Britain," the PM added.

"That was true in 1914, in 1940 and in 1989. Or, you could add 1588, 1704 and 1815... And if things go wrong in Europe, let's not pretend we can be immune from the consequences."

Vote Leave pointed to analysis by the Historians for Britain group, which described the suggestion the EU had prevented wars as "groundless" and "historically illiterate".

It comes after former MI6 boss Sir John Sawers warned leaving the EU would make the UK "less safe".

He said the UK would be shut out of decisions on the "crucial" issue of data sharing.

However, Justice Secretary Michael Gove - who backs the campaign for the UK to leave the EU - said Sir John was "flat wrong".