Tabloid New York Post referred to the book 'Clinton Cash' and said that the Clinton Foundation received between USD 1 million and USD 5 million in 2008 from Singh.
In its report, the Post said the 2008 donation by Singh was made as the US Congress debated the approval of the landmark India-US civil nuclear deal.
The book's author Peter Schweizer speculates whether Singh was a conduit for other powerful interests in India pushing for approval of the nuclear deal.
"If true, that meant Singh had given between 20 and 100 per cent of his entire net worth to the Clinton Foundation!" Schweitzer says in the book according to The Post.
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In New Delhi, telephone calls to Singh to seek his reaction went unanswered.
However, both the Clinton Foundation and her campaign have strongly refuted the suggestions of any wrongdoings and have maintained that there was transparency in receiving donations for the foundation's public cause.
Both the State Department and the White House have refused to comment on the questions and controversies surrounding the funding of the Clinton Foundation.
A recent report after Clinton announced her presidency bid, The New York Times reported that "a flow of cash" made its way into the Clinton Foundation during a deal that gave the Russians control of one-fifth of all uranium production capacity in the US.