The Australian markets had their best day since 1980. Photo: Wikimedia Commons

Australian stocks enjoyed their biggest one-day gain ever on Monday as the rate of new virus infections slowed and the government unveiled fresh stimulus measures to support the struggling economy.

The ASX 200 surged 7.0%, or 339.00 points, to 5,181.4o, while the broader All Ordinaries rallied 6.56%, or 319.80 points, to 5,194.00, its strongest day since 1980.

The performance contrasted with general weakness in other Asian markets, and reflects optimism around the trending of new coronavirus infections in Australia, which rose only 5.6% from Sunday to Monday, according to data compiled by AFP. 

The rate of new infections has been falling since March 22 as federal and state governments have ramped up restrictions on movement to choke off the spread of the disease.

Analysts said investors were also buoyed by continued government action to counter the economic impact of the shutdowns, including a A$130 billion (US$80 billion) income support plan unveiled after the close of trade Monday but widely expected. 

The plan brought total government spending on protection from the outbreak to A$320 billion, which is more than 16% of gross domestic product.

The government’s last annual budget, released in April 2019, called for total spending in the 2019-2020 fiscal year of $500 billion.