SAO PAULO, June 20 (Reuters) - Brazil's Sao Paulo state gave final approval on Thursday to privatize water utility firm Sabesp, which can launch a share sale in coming days.

Sao Paulo plans to privatize Sabesp through an unusual two-part share offer, as the state decided the company must get a strategic investor take a 15% stake in the firm and hold the shares at least the end of 2029.

The state's council for privatizations had approved a minimum price per share in the offer and the minimum demand the successful bidder for strategic investor must get, the state said in a statement.

The state said the minimum price and demand will not be disclosed before share sale conclude.

Sao Paulo, which owns some 50% of Sabesp, intends to reduce its stake to about 18% through the deal. (Reporting by Andre Romani and Patricia Vilas Boas; Editing by Aida Pelaez-Fernandez and William Mallard)