David Pecker, chief executive of the company which publishes the National Enquirer, was granted immunity in the Michael Cohen probe, according to reports.
American Media Inc boss Mr Pecker, a longtime friend of US president Donald Trump, met with prosecutors to describe the involvement of the president and Mr Cohen – Mr Trump's former personal lawyer – in “hush money” deals to women before the 2016 presidential election, the Wall Street Journal reported.
Another AMI executive, Dylan Howard, also received immunity, Vanity Fair and the Wall Street Journal reported. Prosecutors in New York declined to comment.
It is claimed court papers connected to Mr Cohen say Mr Pecker offered to help Mr Trump squash negative stories during the 2016 election campaign.
The Journal said Mr Pecker shared details with prosecutors about payments Mr Cohen says Mr Trump directed to buy the silence of two women alleging affairs with him.
It comes after Mr Cohen pleaded guilty to charges of campaign finance violations, tax evasion and bank fraud earlier this week.
He told a Manhattan court that Mr Trump had directed him to arrange payments before the election to silence two women who said they had sex with Mr Trump.
The president has denied having sex with the women.
Mr Trump initially denied knowing anything about Mr Cohen's action, before acknowledging he had reimbursed him for payments made in 2016 to Stormy Daniels, an adult-film actress.
In an interview with Fox News, Mr Trump said he paid Mr Cohen out of personal funds, and that the payments were intended to resolve a personal matter – not to benefit his campaign.
Additional reporting by Reuters
