Petreleo Brasileiro SA, or Petrobras, expects to close agreements by the end of this year for some of the eight refineries it is selling as part of its program of asset divestment, Chief Executive Officer Roberto Castello Branco said Tuesday.

None of the companies considering bidding on the refineries has shown signs of losing interest, Mr. Castello Branco said during an online interview organized by Banco Safra SA. Some of the potential bidders have asked Petrobras to delay the deadline for submitting bids until June, Mr. Castello Branco said.

Petrobras announced last year that it plans to sell eight of its refineries in Brazil, and the process of selling four of those is more advanced. The company is carrying out a program to sell older, less productive oil fields and other assets to cut debt and focus its investment on its rich new fields off the coast of Rio de Janeiro and Sao Paulo states.