The Spanish blue-chip utility Iberdrola is shaping up as a frontrunner to buy Infratil's majority stake in Tilt Renewables, the Australian newspaper reported.
NZX-listed Tilt owns wind and solar farm assets in Australia and New Zealand.
The newspaper said Iberdrola was looking to lift its exposure to the Australian market at a time when the sector is in hot demand.
New Zealand-based infrastructure investor Infratil has launched a strategic review of its 65.6 per cent stake Tilt for a potential sale.
The review follows approaches to Infratil by AustralianSuper, which this month hoped to buy Infratil for $5.4 billion.
Infratil has rejected the offer as being too low.
Iberdrola's website says it is a global energy leader, the "number one" producer of wind power, and one of the world's biggest electricity utilities in terms of market capitalisation.
"We have brought the energy transition forward two decades to combat climate change and provide a clean, reliable and smart business model," the site says.
Infratil said early this month that it had hired Goldman Sachs to undertake a strategic review of its stake in Tilt after the infrastructure investor received a number of enquiries from potential buyers.
Tilt's shares last traded at $6.00 - having gained 76 per cent over the last 12 months.
At that price, a 65.5 per cent stake would be worth $1.5b.
Infratil last traded at $7.21, giving it a market capitalisation of $5.2b.