The HMAS Toowoomba set sail for the Strait of Hormuz on Monday to defend oil tankers from Iranian attacks against a backdrop of deteriorating relations between the US and Iran.

"A large part of our oil flows through the strait so it's important not just for Australia but also for the globe that the Strait of Hormuz is peaceful and there is freedom of navigation for all commercial vessels," Senator Reynolds said.

It is possible the ship could be re-tasked depending on the volatility of the region.

The new tasks - beyond protecting freedom of navigation - could be counter-piracy, counter-drug running or counter-terrorism.

The federal opposition supports the deployment, just as it did when Australia sent a surveillance plane and handful of troops to the Middle East late last year.

But Labor will not support sending any more resources to the Persian Gulf.

Tensions between the United States and Iran have escalated in recent weeks after Donald Trump ordered the killing of Iranian general Qasem Soleimani.

Iran responded to the assassination by launching missiles at several US-led military bases in Iraq.

Australian Associated Press