By SAM GREENHILL, Daily Mail

Last updated at 10:33 12 June 2006

Britain and Europe face being overrun by mass migration from the Third World within 30 years, a senior Royal Navy strategist claimed yesterday.

In an apocalyptic vision of security dangers, Rear Admiral Chris Parry forecast 'reverse colonisation', where migrants become more dominant than their hosts.

He said the seeds of the problem were spiralling population growth and environmental destruction.

In the competition for resources, many would flee their homelands and head en masse for better places such as Britain.

The Internet, cheap foreign travel and free international phone calls would hasten the demise, he said, because new migrants would stay connected with their homelands rather than assimilate into the host country's culture.

His prognosis is that Western civilisation faces a threat on a par with the collapse of the Roman Empire after the 5th century invasion of Rome by the Goths, the East Germanic tribe.

And he said the process could start within ten years with African pirates attacking yachts and beaches in the Mediterranean.

Admiral Parry is head of the Ministry of Defence unit tasked with identifying future threats to Britain's security.

He said: 'Globalisation makes assimilation seem redundant and old-fashioned.

'The process acts as a sort of reverse colonisation, where groups of people are self-contained, going back and forth between their countries, exploiting sophisticated networks and using instant communication on phones and the Internet.'

Admiral Parry, 52, an Oxford graduate who was mentioned in dispatches in the Falklands War, warned in a presentation last week that the world was heading for a cataclysmic security breakdown.

Although it would start in the Third World, the instability would seep into the West via the Mediterranean.

'At some time in the next ten years it may not be safe to sail a yacht between Gibraltar and Malta,' he warned.

He predicted that as flood, water shortages, agricultural decline or starvation strike, the most dangerous zones would be Africa, especially the northern half, and the Middle East and central Asia.

The flashpoints would also be regions affected by radical Islam.

With rural areas of Third World countries falling into ruin, millions would be forced into towns and cities, with the result that large metropolises such as Mexico City face becoming ungovernable.

In an effort to control population growth, some countries might be tempted to copy China's 'one child' policy, but with the widespread preference for male children this would produce a ratio of boys to girls as much as 150 to 100.

'When you combine the lower prospects for communal life with macho youth and economic deprivation you tend to get trouble, typified by gangs and organised criminal activity,' he said.

He pinpointed 2012 to 2018 as the period when the current global power structure was likely to crumble, with the United States's superpower status challenged by the rise of nations such as China, India, Brazil and Iran.

Admiral Parry, whose slogan was 'old dog, new tricks' when he commanded the attack ship HMS Fearless, delivered his vision in the presentation to senior officers at the Royal United Services Institute in London.

He did not claim all the threats would come true, but warned what was likely to happen if problems were not addressed by politicians.

Lord Boyce, a former Chief of Defence Staff, said of the analysis: 'Bringing it together in this way shows we have some very serious challenges ahead.

'The real problem is getting them taken seriously at the top of the Government.'