Australia-based Sydney Airport Holdings has received a sweetened non-binding takeover offer of $17.4bn (A$23.6bn) from a consortium of infrastructure investors called the Sydney Aviation Alliance.

The consortium comprising IFM, QSuper and Global Infrastructure Partners revised their offer to acquire 100% of the stapled securities in Sydney Airport (SYD) at an indicative price of A$8.75 per share.

Besides, Sydney Airport intends to grant the consortium an opportunity to perform due diligence on a non-exclusive basis, which will enable the consortium to ‘put forward a binding proposal, subject to entry into a non-disclosure agreement on acceptable terms.’

The due diligence is expected to take four weeks after entering the non-disclosure agreement.

If the consortium makes an acceptable binding proposal, the Sydney Airport board could consider the latest bid in the case of no superior offer.

However, the board added that there is no certainty that the new proposal or provision of the due diligence would lead to a binding offer.

Previously, Sydney Airport rejected two proposals of Sydney Aviation Alliance, citing that the proposed bids undervalued the airport operator.

In July, it rejected the $16.5bn (A$22.26bn) buyout bid from the consortium as it sought higher bids for the asset.

Last month, Sydney Airport again turned down a revised $16.81bn (A$22.80bn) buyout bid from the consortium while indicating that it is ready to consider a higher offer.

IFM already holds a stake in Melbourne, Brisbane, Perth and Adelaide while QSuper has a stake in Britain’s Heathrow Airport (LHR). Global Infrastructure reportedly invested in the UK’s Gatwick (LGW) and London City (LCY) airports.