THE supervisor of a trader convicted of making false entries that eventually cost his firm US$81 million (S$122 million) pleaded guilty on Tuesday to helping facilitate the scam.

Takayoshi Wada, 46, admitted that he helped his then-colleague at Singapore-based Mitsui Oil (Asia), Noriyuki Yamazaki, report inaccurate prices of Naphtha, a petrol-based product.

Yamazaki, who pleaded guilty in February, is appealing against his five-year jail term.

The false price information entered on a spreadsheet helped disguise huge losses that Yamazaki, 37, had run up in his trading.

The cover-up surfaced in November 2006 when Mitsui in Japan conducted its own investigations after discovering the trading losses at its Singapore unit Misui Oil (Asia), which has since wound up operations.

Wada, who was general manager of trading and Yamazaki's boss, was accused of conspiring with Yamazaki in making the false entries by not disclosing the matter to Mitsui Tokyo.

This was despite Wada being fully aware that Yamazaki was providing false data relating to the prices of these naphtha trades to conceal losses from Japan.

Judge Jasvendar Kaur postponed sentencing to next month. Wada faces up to seven years' jail and fines of up to $10,000.