The 34-year-old has been a free agent for the past month after running down his previous Blaugrana contract, as Barca desperately attempt to find a solution and tie him to fresh terms.
Ronald Koeman's side have been under pressure to offload some of their big earners in order to comply with La Liga's wage bill, which is understood to have created a stumbling block in negotiations.
However, Sport now claims that Messi has now agreed to put pen to paper on a new five-year deal with Barcelona, which will keep him at the club until he turns 39.
The report adds that Barca president Joan Laporta must still trim his side's squad before Messi can be registered for the new season, and the Argentine has agreed to a 50% pay cut in order to remain in Catalonia.
An announcement on a new deal for Messi - who is currently enjoying time off in Ibiza with former Barcelona teammate Luis Suarez - will supposedly follow within the next few days.
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