Leahy and another investor, Ted Maye, who was also released last week, had travelled to Monaco almost two months ago to confront the former executive chairman of Langbar, Mariusz Rybak, as to the whereabouts of millions of euro worth of investor funds that had been ploughed into the firm. All charges against Leahy were dropped by the Monaco courts.

The Sunday Tribune two men were about to be released.

Leahy, who lives in Sligo, was one of hundreds of investors who lost substantial amounts of money after forensic accountants found no trace of up to 500m in assets that Langbar, which had been co-founded by Rybak, claimed to hold in Brazil and the Netherlands.

The UK's Serious Fraud Office is now investigating the company, while its new executive chairman, David Buchler, is attempting to trace the missing funds on behalf of investors.

Buchler is suing Rybak and two other former directors for over 40m, claiming"deceit and conspiracy to defraud".