In attendance were Donald Trump’s eldest son Donald Trump Junior, then-campaign aide and current White House advisor Stephen Miller, US defence contractor Erik Prince and George Nader, a top advisor to the crown Prince of the United Arab Emirates already of interest to the Mueller investigation.
Mr Zamel reportedly laid out the capabilities of his international firm, which employs former Israeli intelligence officers and harvests public data to aid its clients.
A lawyer for Mr Trump Jnr has denied any deal was struck.
According to The New York Times, a company connected to Mr Zamel had also been working on a proposal for “social media manipulation” that involved using thousands of fake social media accounts to promote Mr Trump’s candidacy on platforms like Facebook in the run up to the poll.
In a statement provided to SBS News on Tuesday, Mr Zamel's lawyer Marc Mukasey, said his client "offered nothing to the Trump campaign, received nothing from the Trump campaign, delivered nothing to the Trump campaign and was not solicited by, or asked to do anything for, the Trump campaign".
"Media reports about Mr Zamel's engaging in 'social media manipulation' are misguided. Mr. Zamel's companies harvest publicly available information for lawful use," he said.
But the emphatic rejection of any wrongdoing has failed to dampen the newfound interest in the reclusive Australian, whose business dealings are now being dissected on US talk shows and in Israeli newspapers.
And Mr Mueller’s interest has also been piqued, according to The Wall Street Journal, which reported on Tuesday that the investigation has been conducting interviews about the work of Mr Zamel.
It follows previous reports that Mr Zamel appeared before a grand jury after federal agents detained him at a Washington airport in February and briefly seized his electronic devices. According to The New York Times, he gave evidence to Mr Mueller about his links to American-Lebanese businessman Mr Nader.
Mr Mukasy told SBS News at the time that his client was not under suspicion. “He is simply a witness,” he said.
The intense interest is a marked shift for Mr Zamel, who largely kept a low profile while building up several private consultancy groups, including one billed as the world’s first "crowd-sourced consultancy firm" Wikistrat. Another, Psy Group, has little public profile but boasts on its motto to “shape reality”.
There is little online record of Mr Zamel, who has left all public appearances to the company's Chief Technology Officer, fellow Australian Daniel Green, or other academics in Wikistrat's ranks.
Mr Zamel moved to Israel to study counter-terrorism after completing a mining engineering degree at Sydney's UNSW. But he is not the first member of his family whose ties to prominent New Yorkers have caught the media’s eye.
Mr Zamel’s parents, Gary and Karyn, made the Sydney property pages last year when they sold a three-storey Point Piper home, which once belonged to Lachlan Murdoch, the son of media mogul Rupert, for $33 million.