MADRID (Reuters) -Spanish lender Sabadell is telling retail shareholders that they may have until 2025 before deciding on BBVA's 12.23 billion euro ($13.3 billion) hostile takeover attempt, as it seeks to stave off the bid.

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.

Retail investors make up close to half of Sabadell's shareholder structure.

BBVA made an all-share offer for Sabadell last month, which was rejected, prompting the Spanish bank to turn hostile in its pursuit of its smaller rival.

Last week, Spanish bank BBVA asked the stock market supervisor CNMV to authorise its takeover offer for Sabadell, a potential tie-up of lenders that Madrid opposes.

BBVA had said that the process could take six to eight months, before formally going to shareholders. The offer needs a minimum approval of 50.01% of Sabadell shareholders.

($1 = 0.9185 euros)

(Reporting by Jesús Aguado; Editing by Tommy Reggiori Wilkes, Jan Harvey and Emelia Sithole-Matarise)