[SINGAPORE] The anonymous blog Iceberg Research issued its third report on commodity trader Noble Group Ltd on Saturday, saying that the Hong Kong-headquartered group had substantially understated its gross and net debt. "We are aware of the report and are reviewing it," a Noble spokesman told Reuters by email on Saturday.

This follows Iceberg's reports last month when it accused the Singapore-listed company of inflating assets by billions of dollars and questioned its accounting practices.

Noble, one of Asia's biggest commodity traders, has rejected the claims and linked the little-known research firm to an employee it fired in 2013.

Noble's shares have lost as much as US$1.8 billion in market value following the reports and the company has pledged to provide more disclosures to improve transparency. "There are an impressive series of red flags drawn when reviewing Nobles governance," Iceberg said in its 31-page report on the company's governance and debt.

Little is known about Iceberg, which has declined to comment on its background, analysts or its methodology. It said, however, that it did not have a short position on the company. Iceberg has released its reports via social media and blogs.

Commodity traders like Noble can make attractive targets for activist short-sellers alleging accounting anomalies, since such companies often rely on complex methods to value commodity contracts and derivatives on their books.

REUTERS