Singapore Power is selling part of its stake in an Australian utility firm to China's State Grid Corporation for A$824 million, which works out to slightly over S$1 billion.

State Grid will buy a 19.9 per cent stake in SP Ausnet from SingPower, SingPower said on Friday. SP Ausnet is listed on the Singapore Exchange.

After the sale, SingPower will still be the largest shareholder in SP Ausnet with a 31.1 per cent stake.

Separately, State Grid will also buy a 60 per cent stake in SingPower's wholly owned unit SPI (Australia) Assets, which is an Australian energy infrastructure company.

SingPower did not disclose the transaction amount.

The two deals are estimated to be worth more than A$5 billion combined, according to the Australian Financial Review.