Lucas, currently with Sao Paulo, will move to France in January.
"I can clarify how things went, seeing as I was the person hired by the player and his entourage to look after his interests in Italy," agent Roberto Calenda told Sky Sport Italia.
"Inter began courting him a year and a half ago. Lucas' family visited Milan and saw a Champions League game at San Siro when Claudio Ranieri was the Coach."
The British media had suggested Manchester United were very close to an agreement, but Calenda insists that was never an option.
"At the end of the day the player had chosen Italy and said yes to Inter. It wasn't just a verbal agreement, as he had authorisation from Sao Paolo.
"However, this opened the door for PSG, as Sao Paolo had already confirmed they were willing to sell. Inter had the opportunity to close the deal, but they chose not to because of the financial crisis."