* ASX benchmark posts biggest intraday pct fall since Aug 5

* Ampol slumps on stake sale in convenience stores property trust

* NZ benchmark index posts best intraday pct gain since June 25

Aug 17 (Reuters) - Australian shares fell on Monday as the country's second-most populous state reported its deadliest day of the COVID-19 pandemic, with financial stocks leading the retreat.

The S&P/ASX 200 index was down 0.9% to 6,073.10 by 0108 GMT in its biggest intraday percentage drop since Aug. 5. Last week, it gained 2%.

Victoria state, which extended the state of emergency by four more weeks on Sunday, reported its biggest daily death toll on Monday with 25 fatalities and 282 new infections.

Index heavyweight financials dropped 1.7% and led declines on the benchmark. The "Big Four" banks lost between 1.1% and 2.3%.

Among other losers, mid-sized lender Bendigo and Adelaide Bank lost 5.6% and was headed for its worst day in more than two months as its annual profit nearly halved.

Ampol Ltd slid 4% after Australia's biggest fuel supplier said it would sell a 49% stake in a convenience stores property trust to Singaporean sovereign wealth fund GIC and Charter Hall Group for A$682 million.

Technology stocks fell 1.1%, with EML Payments Ltd and Computershare Ltd losing 2.6% and 2.3%, respectively.

New Zealand's benchmark S&P/NZX 50 index advanced 1.1% to 11,576.15 in its biggest intraday percentage gain since June 25.

Retirement village operator Summerset Group Holdings was the biggest boost to the benchmark, despite a 6% fall in half-year profit.

New Zealand's prime minister, Jacinda Ardern, postponed the country's general election by a month to Oct. 19 as the city of Auckland remains in lockdown due to a new outbreak of the coronavirus. (Reporting by A K Pranav in Bengaluru; Editing by Subhranshu Sahu)