Australian shares are poised to fall on Monday as escalating US-Iran tensions, including the seizure of an Iranian cargo ship and threats of retaliation that have put a fragile ceasefire at risk, rattled global markets and pushed oil prices sharply higher.

On April 17, the S&P 500, the Nasdaq Composite, and the Dow Jones Industrial Average rose 1.2%, 1.5%, and 1.8%, respectively.

In corporate news, Viva Energy Group (ASX:VEA) said its fire-hit Geelong refinery is expected to produce diesel and jet fuel at about 80% of capacity and petrol at roughly 60% of capacity in the short term.

National Australia Bank (ASX:NAB) said it expects fiscal first-half credit impairment charges of AU$706 million as it lifts provisions to reflect risks stemming from the Middle East conflict.

Australia's benchmark index fell 0.1% or 8.1 points to close at 8,946.90 on April 17.