Australian shares fell sharply on Thursday's close, the last trading day before the Easter break, after a speech by US President Donald Trump threatened further attacks on Iran.

The S&P/ASX 200 Index retreated 1.06% or 92.30 points to close at 8,579.50.

President Trump said the US would hit Iran "extremely hard" and send it "back to the Stone Ages." Brent crude futures jumped around 5% to $105 per barrel. Spot gold fell nearly 2% to $4,670 per ounce.

On the domestic front, seasonally adjusted job vacancies in Australia rose 2.7% to 337,900 in the three months to February, according to data from the Australian Bureau of Statistics (ABS). Private-sector vacancies increased 3.2% to 299,000, while public-sector vacancies fell 0.7% to 39,000.

Australia's goods surplus rose to AU$5.69 billion in February from AU$2.26 billion in January, ABS said. Goods exports rose 4.9%, or AU$2.13 billion, to AU$45.65 billion, driven by a AU$1.82 billion increase in non-monetary gold. Goods imports fell 3.2%, or AU$1.3 billion, to AU$39.96 billion, driven by a AU$1.37 billion decrease in non-monetary gold.

The Australian Index of Commodity Prices climbed 2.6% in March when measured in special drawing rights terms on a monthly average basis, after a 1.6% increase in February, the Reserve Bank of Australia said.

In company news, ASX (ASX:ASX) said it is committed to addressing concerns raised in a probe by the Australian Securities and Investments Commission (ASIC), which flagged governance and risk management failures at the exchange operator. In a final report issued the same day, the ASIC said ASX had compromised the resilience of critical market infrastructure to deliver higher shareholder returns. Its shares were 1% lower on market close.

Clinuvel Pharmaceuticals (ASX:CUV) said patient case studies from its ongoing CUV105 study in vitiligo showed repigmentation after 20 weeks of therapy with its drug candidate afamelanotide and adjunct narrowband ultraviolet B phototherapy. Its shares fell 7% on market close, earlier reaching an eight-year low.

Lastly, Synlait Milk (ASX:SM1, NZE:SML) completed the NZ$307 million sale of its North Island assets to Abbott, including the Pokeno manufacturing facility, inventory, and leased Auckland sites. The company received around NZ$283.1 million upfront, with an additional $14 million to be paid later if there are no post-completion claims. Its shares closed up over 1%.