Competition for Australian vehicle heats up after Oxford Properties enters the frame. : Blackstone has increased its offer for Investa Office Fund (IOF) as the battle for ownership of the Australian listed real estate fund heats up. Its original offer of AUD3.1bn was increased to AUD3.2bn (€2bn), but the US private equity firm faces potential competition from Investa Commercial Property Fund (ICPF) and Oxford Properties, which together own 19.99% of IOF, as well as Macquarie, which recently bought 50% of ICPF.