SINGAPORE - Shares of mainboard-listed Noble Group fell sharply on opening on Friday, a day after the commodities and energy trader reported its first quarterly loss in more than three years amid allegations of accounting abuses that the company believes was the work of a disgruntled ex-employee.

Its shares were down 6 cents, or 5.6 per cent, at $1 at about 9:55am, when they resumed trading on Friday after after a suspension the day before.

It was the most active stock with about 52 million shares changed hands, more than twice the average full-day trading volume over the last 30 days.

Noble said on Thusrday that it took a US$438 million writedown, including charges on assets scrutinized by the anonymous Iceberg Research as part of its allegations of accounting malpractice. Falling commodity prices hit revenues at its mining and mineral operations and required more capital for provisions, said the Hong Kong-listed group, which swung to a US$240 million fourth-quarter loss.

Iceberg in its first report on Noble a week ago included allegations that Noble was overstating the value of associate companies including Yancoal Australia Ltd., sparked a decline of as much as 15 percent in the stock over two days.

Noble, which said on Thursday it wrote down the value of Yancoal by US$200 million, believes a "disgruntled" employee fired more than a year ago is behind the reports, Chief Executive Officer Yusuf Alireza said on a conference call.

Mr Alireza denied Noble's writedowns were spurred by the Iceberg reports and said discussions about the impairments began with auditors a month ago.

Noble said on Thursday that Ernst & Young LLP had agreed to sign off on its accounts, hours after flagging a delay in securing the auditor's approval. The delay occurred after the company said Ernst & Young needed more time to review its own internal processes after Iceberg published a second report on Thursday.