The Wall Street Journal on Wednesday fired its highly regarded chief foreign affairs correspondent after evidence emerged of his involvement in prospective commercial deals – including one involving arms sales to foreign governments – with an international businessman who was one of his key sources.

The reporter, Jay Solomon, was offered a 10% stake in a fledgling company, Denx LLC, by Farhad Azima, an Iranian-born aviation magnate who has ferried weapons for the CIA. It was not clear whether Solomon ever received money or formally accepted a stake in the company.

“We are dismayed by the actions and poor judgment of Jay Solomon,” Wall Street Journal spokesman Steve Severinghaus wrote in a statement to the Associated Press. “While our own investigation continues, we have concluded that Mr Solomon violated his ethical obligations as a reporter, as well as our standards.”

Azima was the subject of an Associated Press investigative article published on Tuesday. During the course of its investigation, the Associated Press obtained emails and text messages between Azima and Solomon, as well as an operating agreement for Denx dated March 2015, which listed an apparent stake for Solomon.

As part of its reporting, the Associated Press had asked the Journal about the documents appearing to link Solomon and Azima. The relationship was uncovered in interviews and in internal documents that Azima’s lawyer said were stolen by hackers.

“I clearly made mistakes in my reporting and entered into a world I didn’t understand,” Solomon told the Associated Press on Wednesday. “I never entered into any business with Farhad Azima, nor did I ever intend to. But I understand why the emails and the conversations I had with Mr Azima may look like I was involved in some seriously troubling activities. I apologize to my bosses and colleagues at the Journal, who were nothing but great to me.”

Two other Denx partners – ex-CIA employees Gary Bernsten and Scott Modell – told the Associated Press that Solomon was involved in discussing proposed deals with Azima at the same time he continued to cultivate the businessman as a source for his stories for the Journal. Bernsten and Modell said Solomon withdrew from the venture shortly after business efforts began and that the venture never added up to much. They provided no evidence as to when Solomon withdrew.

The emails and texts reviewed by the Associated Press – tens of thousands of pages covering more than eight years – included more than 18 months of communications involving the apparent business effort. Some messages described a need for Solomon’s social security number to file the company’s taxes, but there was no evidence Solomon provided it.

Denx was shuttered last year, according to Florida business registration records.

In an April 2015 email, Azima wrote to Solomon about a proposal for a $725m air-operations, surveillance and reconnaissance support contract with the United Arab Emirates that would allow planes to spy on activity inside nearby Iran. Solomon was supposed to ferry the proposal to UAE government representatives at a lunch the following day, the email said.

“We all wish best of luck to Jay on his first defense sale,” Azima wrote to Solomon, Bernsten and Modell.

Under the proposed UAE deal, Azima’s firms were to manage specially equipped surveillance planes to monitor activity in Iran, Syria, Iraq and Yemen.

In October 2014, Solomon wrote to Azima in a text message: “Our business opportunities are so promising.”

In another message that same month, Solomon asked Azima whether he had told a mutual friend about their business plans.

“Hell no!” Azima replied.

The emails show Solomon’s relationship with Azima began professionally, as the reporter cultivated the businessman as a source of information about Iranian money in a Georgian hotel deal and other matters. A review of Solomon’s published work over the past four years indicated Azima never appeared by name in the newspaper.

The hacked materials also demonstrate that Azima cultivated close relationships with fellow Western and American journalists, including those at the Associated Press, and frequently communicated with them by phone, text and email. None appeared to involve the same level of personal involvement or referenced potential business deals.

Veteran journalists at prominent outlets such as the Journal have contacts, expertise and influence that can be valuable in the business world, said Kelly McBride, a vice-president for the Poynter Institute, a not-for-profit journalism education center. But seeking to exploit those assets while a journalist would betray readers’ trust in a reporter’s impartiality.

“You can’t have conversations about business deals outside your employment,” she said.