Lionel Messi says former Barcelona president Josep Maria Bartomeu lied to him repeatedly over the course of several years but he won't rule out staying at Camp Nou beyond this season despite wanting to leave four months ago.

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Messi, 33, is out of contract in June and is free to negotiate a pre-contract agreement with other clubs from Jan. 1. However, the forward says he will not make any decision about his future until the summer.

In an extensive interview with La Sexta's Jordi Evole, Messi also lifted the lid on why he tried to quit Barca in August, spoke about a possible reunion with Paris Saint-Germain's Neymar and detailed how his relationship with Bartomeu, who resigned in October, deteriorated.

"I had been telling [Bartomeu] for six months that I wanted to leave and asking for his help and he just said 'no, no, no," Messi said. "So, I sent the burofax as a last resort to show I was serious, to make it official.

"I'm eternally grateful to the club for everything but it felt like a cycle had ended and I needed a change. I knew this would be a transition year and I want to fight for the Champions League and league titles.

"The president didn't want to let me go and then he started to leak things to make me look like the bad guy. Then everything that happened happened, but I am still calm that I did what was right at that moment."

Messi said he was appalled at how Bartomeu forced friend and teammate Luis Suarez out, letting him leave for title rivals Atletico Madrid for free, but wouldn't go into details about the lies the former president had told him.

"He [lied] about many things," Messi laughed. "Honestly, so many, but I prefer not to go into private things that happened -- but I can assure you it was many things over several years."

Bartomeu stepped down in October and a new president will be appointed on Jan. 24. Before then, Messi will be able to talk with other clubs, although he insists he is only focused on the current campaign.

"No [I won't talk with other clubs because] I don't have anything clear until the end of the year," the Argentina international added. "I am going to wait for the season to finish. The important thing is to think about the team and to try and win titles, not to get distracted with other issues.

"I don't know what will happen. I am focused on what we have in front of us over the next six months. It would not be right to tell you what I am going to do after that because even I don't know."

Ex-president Joan Laporta and Victor Font are the favourites to replace Bartomeu and will be tasked with trying to convince Messi to sign a new deal.

Messi wouldn't position himself with any of the candidates but will listen to the incoming president's plans before making any decision on his future.

Manchester City and PSG are the two best-placed clubs to sign him in Europe, but Messi wouldn't be drawn on either, although he did say "it's always been a dream to play in the United States" before he retires.

Creating a project to tempt Messi to stay will be tough for the new president given Barca's financial problems.

"The club is very bad [financially], very bad," he said. "It's going to be difficult to return to where we were. It won't be easy for the new president to turn things around. I hope whoever wins does things well to get this great club back to where it deserves to be."

Neymar recently said he would like to play with Messi next season. Messi said he still speaks to the Brazilian -- and did so earlier this month when Barca drew PSG in the Champions League -- but he doubts a Camp Nou reunion would be economically possible.

"It's going to be tough to sign quality players because there's no money," Messi said. "It's tough to bring Neymar here. [Even if he] accepts a smaller salary, how do you pay PSG? The new president will have to be very intelligent and get things in order."

Messi also said he has never seen a psychologist even though he knows he should, backed Barca coach Ronald Koeman, reiterated that there are no problems between him and Antoine Griezmann and said he sees himself as a sporting director, not a coach, when he retires.