Philippine conglomerate Ayala Corp said it would not improve its takeover offer for Australia's Infigen Energy further after a month-long bidding war for the wind and solar firm.

The announcement comes a day after rival Spanish power generation company Iberdrola said its offer for Infigen Energy, due to close on July 30, was now unconditional. Infigen has asked its shareholders to reject the Ayala bid.

Infigen shares closed at A$0.90 on Friday, marginally above Iberdrola's offer as investors hoped for a higher bid to emerge from UAC Energy Holdings, a joint venture of Ayala's AC Energy and Hong Kong-based UPC Renewables Group.

Iberdrola's offer was backed by Infigen in June after it improved its offer by 3 cents to A$0.89 a share, valuing the company at A$856 million ($598 million). The bid was approved by Australia's Foreign Investment Review Board.

UAC Energy said it made no final decision regarding its stake in Infigen when its offer closes.

($1 = 1.4310 Australian dollars)

(Reporting by A K Pranav in Bengaluru; Editing by Muralikumar Anantharaman)