MADRID, May 28 (Reuters) - Spanish lender Sabadell has kicked off the process of trying to persuade retail shareholders not to back BBVA's 12.23 billion euro ($13.3 billion) hostile takeover attempt, telling them they may have until 2025 before needing to decide.

In a letter being sent to Sabadell's shareholders this week, Sabadell chairman Josep Oliu said investors do not have to take any decisions at this stage, "as the takeover bid process may continue until the end of 2024, or even 2025".

"It would be then that the board of Banco Sabadell would issue a public and detailed recommendation regarding the bid and you would have to make your decision," Oliu said in the letter seen by Reuters.

($1 = 0.9185 euros) (Reporting by Jesús Aguado; Editing by Tommy Reggiori Wilkes and Jan Harvey)