Now it can be revealed Britain is also encouraging Australia to contribute. Prime Ministers Boris Johnson and Scott Morrison discussed the importance of international cooperation to protect shipping and defend freedom of navigation during a telephone call overnight.
Mr Morrison reaffirmed that Australia is still considering its position.
The British request was directly made to Defence Minister Linda Reynolds on Sunday night when she spoke with her new counterpart Defence Secretary Ben Wallace.
"I can reiterate that the Australian Government remains very concerned about the increased tensions in the Strait of Hormuz, and we are considering the American request, and also now the request from the United Kingdom, but we have not yet made any decision," Senator Reynolds told reporters at Garden Island in Sydney on Wednesday.
Australia's contribution could be limited to sending an aircraft for reconnaissance and surveillance rather than a naval presence, which the government would prefer to be kept in the Indo-Pacific rather than the Middle East.
Britain has despatched HMS Duncan, a Type 45 Destroyer to the Strait to join HMS Montrose, a Type 23 frigate, to escort merchant vessels through the Strait, which is the busiest narrow shipping passage in the world with 20 per cent of the worlds oil passing through it every year.
"Our aim is to build the broadest international support to uphold freedom of navigation in the region, as protected under international law," Foreign Secretary Dominic Raab said.
Tensions flared in the region last month, after Britain seized an Iranian oil tanker near Gibraltar accusing it of breaching sanctions on Syria.
Iran retaliated by seizing three tankers, including the British-flagged Stena Impero.
It comes against the backdrop of US President Donald Trump's hardened position on Iran, including tearing up the nuclear deal brokered by his predecessor Barack Obama, which Australia and Britain still support, and imposing sanctions on Iran.
Iranian President Hassan Rouhani warned on Tuesday that shipping might not be safe in the Strait of Hormuz, adding that "war with Iran is the mother of all wars".