Convicted Democratic Party fundraiser Sant Chatwal got an invitation to a State Department lunch for then Indian Prime Minister Manmohan Singh in 2009 through Hillary Clinton's aide Huma Abedin, according to emails obtained by a conservative activist organisation.
During that time, Chatwal was secretly funnelling illegal political contributions to Democratic Party politicians for which he was later convicted.
On Thursday, Judicial Watch released the emails, which were among a trove it obtained through a court order.
The organisation was following up the controversy over Clinton using a private email server while she was the Secretary of State.
Abedin, who is of Indian and Pakistani descent, served as Clinton's deputy chief of staff in the State Department and later as the vice chair of her presidential campaign.
New York hotelier Chatwal was considered close to the Clintons, travelling to India with former US President Bill Clinton, and serving as a trustee of the Clinton Foundation.
In a November 2009 email to Abedin, Chatwal asked to be invited to US President Barack Obama's State Dinner for Singh.
"We have no control over the White House State Dinner," Abedin replied using an email address on "clintonemail.com" server.
"But, Hillary is hosting the state lunch for the Prime Minister with Vice President (Joe) Biden at the State Department and you should be receiving your invitation to that soon. Will be the same day (as Obama's dinner), November 24," she wrote.
A federal judge ordered the State Department in 2016 to give some of the emails to Judicial Watch, which made the demand under the freedom of information laws.
In 2014, a federal judge in Brooklyn found Chatwal guilty of making illegal election contributions of $180,000 to three candidates between 2007 and 2011 and tampering with witnesses.
He admitted in court that to overcome the legal limits on contributions an individual can make to a candidate, he made his employees send in the funds in their own names and repaid them.
The federal prosecutor, Loretta Lynch, who was later promoted to Attorney General by Obama, did not identify the three candidates in her press statement about the conviction.
But The New York Times and other media said that one of them was Clinton.
Chatwal was not given a prison sentence, even though he faced a maximum sentence of 25 years in prison. Despite prosecution protests, he received only three years of probation and a $500,000 fine.
Clinton's use of a private email server for official business as the Secretary of State was considered a violation of government rules because of the security risks and was issue in 2016 presidential election.
Clinton handed over 55,000 pages of emails from her server to the State Department during the investigations into the use of the private server.
Judicial Watch said that the Abedin-Chatwal emails it obtained through court order were not a part of those emails.