British expatriates are ideal targets for chancers and conmen, warns David Marchant, publisher of the Miami-based Offshore Alert magazine. "A typical expat is financially successful," he says. "Also, being strangers in a foreign land, expats tend to work and socialise together, forming a group of people that is easy for conmen to recognise and infiltrate."

Many are elderly too, and more vulnerable to sharp practice by fraudsters, who themselves are often based in offshore havens or countries with little or no financial regulation.

Mr Marchant was the first to raise concerns about Imperial Consolidated, a financial group that sold investments promising returns of 15 per cent a year to UK expats across the world. It collapsed in 2002 after losing up to £200m of investors' money and became the subject of a Serious Fraud Office probe.