Britain aims to become the most hostile country in the world to fraudsters, the government’s top law officer has pledged, in an eye-catching riposte to growing criticism about the lack of big financial crime cases being mounted.

Baroness Scotland, attorney-general, said domestic investigation agencies would soon be giving their assertive US counterparts a “real run for their money”, in spite of London’s failure to bring down large companies or a high-profile individual such as Bernard Madoff.