Josep Maria Bartomeu says Barcelona firmly believe superstar forward Lionel Messi will remain at the club until he retires amid conflicting reports over the progress of contract negotiations. 

Securing the future of the Argentina attacker, whose deal expires in June 2018, is a high priority for the LaLiga champions.

Sources close to Messi this week rejected suggestions an impasse has been reached in talks between the two parties.

And club president Bartomeu, speaking at the announcement of a lucrative new shirt sponsorship, indicated he is confident the 29-year-old will choose to stay at Camp Nou. 

"We are convinced Messi will finish his career [at Barcelona], as it has to happen, he is our leader and we are very relaxed thinking [about] his renewal," he said.

"He's the player who has brought us success all these years."

Messi has been speculatively linked with a move to join former coach Pep Guardiola at Manchester City in recent months, while he has previously hinted at the possibility of playing in his native Argentina before hanging up his boots.