Messi had been plagued by muscular injuries early in the season, but has recently returned to top-form as he has scored a hat-trick in consecutive games, most recently, in Sunday's thrilling 4-3 win away to Real Madrid.
According to Sport24, the four-time World Player of the Year has a contract with the Spanish giants until 2018, but Bartomeu said that talks were going on with the player's father and agents over a deal that would surpass the five-year contract Cristiano Ronaldo signed with Real Madrid in September last year.
Bartomeu also said that there is confidence within the club that the Argentine becomes the best paid player in the world as he is the world's number one player, adding that Messi is Barcelona's 'star' and has a contract until 2018 as they want him to participate in their future.
And contrary to some rumours linking him with a move to free-spending Paris Saint-Germain or Manchester City, Bartomeu is convinced that Messi is determined to remain at Barca for many years to come. (ANI )