Jefferson Smurfit has confirmed the identity of its suitor as US private equity house Madison Dearborn Partners.
An independent committee of directors has now been set up by the Dublin-based firm to "take any appropriate action" relating to MDP's potential bid.
Smurfit revealed it was in preliminary talks with a third party a week ago, sparking a 12% jump in its share price.
Chicago-based MDP was seen as the likely candidate, with speculation that any bid would depend on Smurfit's management remaining on board.
Smurfit confirmed this today, but reiterated the talks were at an early stage and "may or may not lead to an offer being made for part or all of the company".
A statement added: "MDP is one of the largest and most experienced private equity investment firms in the United States.
"Its objective is to invest in companies that have outstanding management teams and the potential for significant long-term equity appreciation."
MDP has a track record in the paper and packaging industry, snapping up the Packaging Corporation of America in March 1999 for £2.2 billion.
Smurfit is the world's largest maker of containerboard and linerboard for corrugated cardboard boxes.
Chairman Michael Smurfit, his brothers Dermot and Alan, and his son Tony own around 10% of shares in the company.