Washington: The first shoe dropped Wednesday, when presumptive Democrat presidential candidate Hilary Clinton was sternly rebuked in the report of a top-level State Department investigation of her controversial use of a private email server – stashed in the basement of her home – while serving as the US's top diplomat.

And she knows not the day nor the hour when the second shoe might drop – that'll be the report of a parallel FBI investigation into references to classified information in dozens of emails moved on the server, including more than 20 which the CIA deemed to be 'top secret.'

But amidst reports that the former Secretary of State had yet to be interviewed by the FBI and that she and her staff had refused to cooperate with the inspector general's investigation, the report cut through the Clinton campaign's 'no-problem' spin, with a declaration that while she had been obliged to discuss her use of the basement server with cyber security officials, there was no evidence that she had done so.

The 78-page report, leaked ahead of its planned release on Thursday, states that State officials "did not – and would not – approve her exclusive reliance on a personal email server to conduct departmental business".