The Financial Services Authority has arrested a 23-year-old man as part of an investigation into a suspected unauthorised foreign exchange trading scheme.
The arrest was made with the assistance of the City of London Police and a search warrant was also executed at one address in East London.
Confirming the arrest, the FSA said the man was suspected of committing offences under the Financial Services and Markets Act 2000 and the Fraud Act 2006.
No one has been charged at this stage in connection with the investigation, which is ongoing, the FSA added.
The regulator also said the arrest is not linked to any other FSA investigations.
Breaching SEC rules
In Leeds since 1969
Latest news and analysis
And vote now for Best Service award
Impact of rates