Roundup: Cameron fears "World War 3" if Britain quits Europe

British Prime Minister David Cameron hinted in a major speech Monday at the British Museum here at the prospect of Britain's exit (Brexit) from the European Union (EU) sparking "World War 3."

When the British public votes on staying within or leaving the EU in a referendum on June 23, they will decide on the destiny of Britain for decades, perhaps a lifetime, said Cameron, adding: "This is a decision that is bigger than any individual politician or government."

Monday's speech by Cameron is being described by commentators as his most emotive speech so far in making the case for Britain to stay in the EU.

Surveys show that one of the strongest reasons among the "stay" camp is that the nations of Europe have been at peace for over 70 years.

No sooner had Cameron ended his speech, did opponents, including some members of his own Conservative Party, condemned his doom-laden message.

Brexit campaigners accused Downing Street of panicking, even though there have been "stay" interventions from Barack Obama, and other world leaders.

Former London Mayor and leading Brexit campaigner Boris Johnson said later: "The principle guarantor of peace and stability on our continent has been NATO, and what worries me now is that it is the European Union's pretensions to run a foreign policy and a defense policy that risk undermining NATO."

It was a point echoed by the former head of history at Cambridge University, Professor David Abulafia, who dismissed the claim that the EU had brought peace to Europe as "historically illiterate." He, and some other academics, insisted it was NATO that had kept Britain safe since 1945.

Rather than focus on the economic reasons to remain in the EU, Cameron instead concentrated on what membership meant for Britain's strength and security in the world.

"The dangerous international situation facing Britain today means that the closest possible cooperation with our European neighbors isn't an optional extra -- it is essential. Now is a time for strength in numbers," Cemeron said, citing threats to security such as that the Islamic State posed.

"For 2,000 years, our affairs have been intertwined with the affairs of Europe. For good or ill, we have written Europe's history, just as Europe has helped to write ours," he said.

The European Union, Cameron said, had helped reconcile countries which had been at each others' throats for decades.

"Britain has a fundamental national interest in maintaining a common purpose in Europe to avoid future conflict between European countries," he said. Endit