INQUIRIES into the scandal in the world copper market have widened to the criminal arena on both sides of the Atlantic.

After the British Fraud Squad was called in at the end of last week, there are reports from New York that the Manhattan attorney general's office has convened a grand jury to investigate copper trading involving Sumitomo Corp of Japan.

Scandal in copper was brought into the open last Thursday when Sumitomo announced it had fired star trader Mr Yasuo Hamanaka (48) It said he had confessed to losses of $8 billion in unauthorised deals.

Traders say his strategies, based on controlling prompt supply from stocks that he hoarded, also seem to have propped up prices on copper when other metals weakened in the early 1990s.

Investigators are now anxious to pursue inquiries among a range of companies that had dealings with Sumitomo in an attempt to discover how Mr Hamanaka was able to evade the system for so long. A spokesman for New York trading firm Global Minerals & Metals Corp said the Manhattan attorney general's office was expected to issue a subpoena to the firm and its founder, Mr David Campbell.

In Britain, the Serious Fraud Office (SFO) and London police have joined inquiries already being pursued by the British markets regulator, the Securities and Investment Board (SIB).