All four shortlisted bidders for a prized Australian power grid have been cleared by Australia's Foreign Investment Review Board (FIRB), in a partial privatization that is all but certain to come under intense political scrutiny.

The final binding bids for the lucrative New South Wales state-government owned asset TransGrid, which owns the NSW electricity grid and fibre optic cable networks in NSW and the Australian capital territory, were received on Monday, with the winning bidder to be announced by year's end.

Among the bids included a Chinese-Australian consortium -- State Grid Corporation of China, Macquarie infrastructure and Real Assets -- a Canada-Australia joint venture, an Abu Dhabi investment firm as well as Kuwaiti and local interests, according to Fairfax Media.

The New South Wales government made clear to bidders they wanted unconditional offers, therefore each consortium was required to see FIRB and other relevant regulatory approval prior to submission on Monday.

Meanwhile it is understood all relevant information to the asset sale had been passed onto relevant authorities to accurately assess the suitability of all bidders.

The decision, due by year's end, is likely to put Australian Prime Minister Malcolm Turnbull in the political headlights following the lease of the Darwin port to China's Landbridge as the Australian public scrutinizes asset sales to foreign investors.

Opposition political parties sighted security fears as part of the port services Australia's and foreign allied navies.

The Darwin port was not subject to FIRB scrutiny, which reviews all Chinese asset purchases over 252 million Australian dollars -- 1 billion for the U.S. and U.K purchases - as it was a state asset and leased, not sold.

Australian authorities dismissed the opposition's security fears after revealing defence officials had given the green light to the lease, however it is a different story with TransGrid which owns cables that support defence bases and intelligence facilities.

A spokesperson for Australian Treasurer Scott Morrison however told Xinhua on Monday all relevant Commonwealth agencies with an interest in the ownership of the "critical infrastructure" were involved in the discussions with all relevant bidders.

The consultations between relevant stakeholders ensured "that the details of each bidding consortium are fully understood and that each consortium is fully aware of national interest requirements," the spokesperson said in a statement.

The NSW government will also maintain significant influence over the assets as the lessor and other regulatory frameworks including the National Electricity Market rules, NSW Treasurer Gladys Berejiklian told Xinhua in a statement.

The next business to be offered in the 30 billion Australian dollar (21.50 billion U.S. dollar) "poles and wires" privatization, electricity distributor Ausgrid, is a potential consolation prize for the losing bidders when expressions of interest open on Tuesday.