A former CIA officer was offered a presidential pardon by an associate of Rudy Giuliani for $2 million, according to The New York Times.
John Kiriakou was sentenced to 30 months in jail in 2012 for revealing the identity of an undercover US intelligence agent.
According to the The New York Times, Kiriakou laughed at the offer, but one of his associates, who was privy to the conversation, alerted the FBI.
Mr Giuliani, a personal lawyer for US President Donald Trump, denies the allegation.
"Two million bucks – are you out of your mind?" Kiriakou recalled saying.
"Even if I had two million bucks, I wouldn't spend it to recover a $700,000 pension," he said.
While Kiriakou's accusation could not be immediately substantiated, Mr Trump previously pardoned people later revealed to have been donors to his 2020 election campaign.
The New York Times believes a sustained lobbying campaign has been organised by those close to Mr Trump, offering presidential clemency for cash.
The newspaper says it spoke to a dozen officials who confirmed the allegations, although this could not be independently verified.
In February, Mr Trump pardoned Paul Pogue, whose family made substantial donations to Mr Trump’s 2020 campaign, according to information released by the Federal Election Commission.
The Texan businessman was accused of failing to pay taxes in 2010. He pleaded guilty to the charges and settled what was owed.
On Monday, CNN reported claims by unnamed sources that Mr Trump was preparing a further 100 pardons prior to the inauguration of president-elect Joe Biden.
According to lawyers Jack Goldsmith and Mark Gluck, writing in the blog Lawfare, the majority of people pardoned by Mr Trump may have advanced "a clear political goal of the president" or may have had a personal connection to him, or his friends.