Australian shares extend gains on COVID-19 vaccine optimism

* Miners, financials top gainers on benchmark

* Australian banks to buy more govt debt - AFR

Sept 8 (Reuters) - Australian shares rose for a second straight session on Tuesday, as optimism surrounding the development of potential COVID-19 vaccines kept investor sentiment high, with miners and financials leading the charge.

Australia will buy about 85 million doses of two potential COVID-19 vaccines if trials prove successful, Prime Minister Scott Morrison said on Monday, with the first batches of the doses expected to be received by early next year.

The agreement between Australia and biotech firm CSL to manufacture two potential vaccines came on Monday as Australia reported its lowest one-day rise in new COVID-19 cases since June 26 in the past 24 hours.

The S&P/ASX 200 index climbed 1% to 6,007.10 by 0030 GMT in low-volume trade, adding to Monday’s 0.3% gain.

About 77.3 million shares had changed hands in early trade, compared with the 30-day average of 767.8 million shares, as stock markets in the United States were closed for a holiday on Monday.

Among gainers, miners were the top boosts to the benchmark index, advancing 1.2% on rising iron ore futures and improvement in exports to China, Australia’s largest trading partner.

Global miners BHP Group and Rio Tinto gained up to 1.4% each.

Heavyweight financials added 1%, with top lenders Commonwealth Bank of Australia and Westpac Banking Corp rising 1% each.

Meanwhile, the Australian Financial Review reported Australian banks would be required to buy up to A$240 billion ($174.84 billion) of new government debt to boost stability and liquidity levels.

CSL added up to 1.5% in its second straight session of gains, helping the healthcare index rise 2.1%.

In New Zealand, the benchmark S&P/NZX 50 index rose as much as 0.5% to 11,916.230.

Heavyweight blue-chip firms were among the top gainers, with Fisher & Paykel Healthcare and dairy firm a2 Milk Co adding about 1.2% each.

$1 = 1.3727 Australian dollars Reporting by Sameer Manekar in Bengaluru; Editing by Subhranshu Sahu