(Adds details on offers from Blackstone, Oxford)
Oct 15 (Reuters) - Investa Office Fund (IOF) said on Monday it has given private equity firm Blackstone four days to match a rival offer by Canada's Oxford Properties Group as the bidding war for the Australian office owner comes to a head.
IOF said in a statement that its board has assessed Oxford's binding proposal and determined it to be superior to the Blackstone offer.
IOF said Blackstone has until Oct. 18 to match or outbid Oxford's offer. A Blackstone spokeswoman declined to comment.
IOF last month postponed a shareholder meeting to vote on Blackstone's offer, choosing instead to engage with Oxford after the Canadian company sweetened its bid.
Oxford upped its offer for IOF to A$5.60 a share, which was A$0.10 higher than Blackstone's latest bid and valued Investa at A$3.35 billion ($2.38 billion).
Blackstone initially bid A$3.08 billion for Investa in May.
$1 = 1.4073 Australian dollars Reporting by Aby Jose Koilparambil; editing by Richard Pullin