An additional 200 million litres of diesel will come into Australia as part of four cargoes coming from South Korea, Malaysia and Brunei.
Two of the cargoes have been bought by BP and the other two by Viva Energy using new taxpayer-backed underwriting powers, with the shipments due to arrive in Australia in late May or early June.
According to the NRMA, Australia uses almost 94 million litres of diesel a day.
Prime Minister Anthony Albanese said the supplies would give an extra buffer against volatility in the fuel market driven by the war in Iran and subsequent blockages of the Strait of Hormuz.
"We will continue to use every measure at our disposal to make a difference," he told reporters from Sydney's Port Botany on Wednesday.
"What we can control is how we respond and we are responding by throwing everything at it.
"What we're doing is continuing to do everything we can to secure as much supply as possible going forward."
Mr Albanese will meet with premiers and chief ministers for a national cabinet meeting on Thursday to discuss fuel issues.
However, no major changes to fuel security strategies are expected from the talks, which the federal government is framing as an update on existing plans.
"It's important that states and territories be informed and it's important that we work together as a nation at what is a very difficult and challenging time for the entire world," Mr Albanese said.
There are 61 fuel ships en route to Australia, with five to arrive in Sydney in coming days.
The announcement of the extra cargoes of diesel comes as farmers are being promised more fertiliser imports as part of a deal struck between the federal government and major companies.
The agreement with chemical suppliers CSBP and Incitec Pivot involves underwriting their purchases to reduce the financial risk of importing fertiliser.
The deal was struck using the government's strategic reserve powers, which are designed to shore up supplies of crude oil, fuel and fertiliser, all of which have been impacted by the strait's closure.
Much of the world's fertiliser usually travels through the key waterway and the Iran war has sent prices for the crucial agricultural commodity soaring.
Under the agreement, government funds will effectively be put up as insurance for importers who are facing rapid price changes because of the war.
The scheme is designed to give companies confidence to buy the supplies they need, even if prices drop shortly after.
Agriculture Minister Julie Collins hailed the fertiliser deals as a significant outcome that would help farmers better manage the upcoming growing season, supporting the nation's food production.
"We understand how critical fertiliser is for Australian farmers, for our food production system and the food security of our region," she said.
Similar deals have been struck with five fuel companies - BP, Viva Energy, Ampol, iOR and Park Fuels - allowing them to buy additional petrol and diesel for the Australian market.
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