TOKYO, March 10 (Reuters) - Japanese insurer Tokio Marine Holdings Inc said on Wednesday it is investigating the validity of insurance policies provided by its Australian unit to speciality finance firm Greensill. Greensill filed for insolvency on Monday after losing insurance coverage for its debt repackaging business and said that its largest client, GFG Alliance, had started to default on its debts. GFG Alliance, which is controlled by Indian-British steel magnate Sanjeev Gupta, has said the group is operationally strong. Bond and Credit Company (BCC), a Tokio Marine unit, had provided $4.6 billion of coverage to Greensill credit notes, according to Australian court filings. “We have concerns about the validity of all Greensill policies and are conducting an investigation,” Tetsuya Hirano, a Tokio Marine spokesman said. He declined further comment. Greensill declined to comment. If Greensill’s lending practices did not meet standards laid out in the insurance contract or was inconsistent with normal accounting rules, then an insurer would have grounds to challenge whether the agreed coverage applied, supply chain experts said. The Tokio Marine spokesman said that the $4.6 billion figure in the court filings did not reflect the likely loss but declined to comment further. Having examined BCC’s business relationship with Greensill, the Japanese company right now sees no need to change its financial forecasts for the year ending this month, Hirano said. When Tokio Marine acquired BCC from Insurance Australia Group (IAG) in 2019, IAG “had in place extensive reinsurance of trade credit insurance agreements that were written by BCC, and Tokio Marine only assumed risk for a minority of the total trade credit insurance agreements,” he added. (Reporting by Makiko Yamazaki in Tokyo and Tom Bergin in London; editing by Carmel Crimmins)