Lachlan Murdoch’s radio business, Nova Entertainment, has admitted it breached the law by failing to lodge dozens of documents with the corporate regulator, as an audit by the Australian Taxation Office reaches its second year.

The billionaire media mogul, who is chair of News Corporation and executive chairman of Fox Corporation, which runs the conservative US television network Fox News, has owned Nova for more than a decade. He has benefited immensely from the private Australian media company, which owns the Nova and SmoothFM radio brands.