UK Trade Minister Liz Truss says she expects her Government to complete a wide-ranging trade deal with Australia within months of exiting the European Union.

Key points: Australia is Britain's seventh-largest trading partner

Australia is Britain's seventh-largest trading partner Commonwealth countries have been touted as stronger trading partners after Brexit

Commonwealth countries have been touted as stronger trading partners after Brexit Australian Trade Minister Simon Birmingham said this would benefit local agriculture

In efforts to reduce the economic impact of Brexit, Britain is looking to line up a series of trade deals with smaller, non-EU countries.

Ms Truss — who is in the middle of a three-nation tour that includes Australia, New Zealand and Japan — said she expected a quick conclusion to trade talks that will begin when Britain leaves the EU.

"The reason that I have chosen to make Australia one of the first countries I have visited as Trade Secretary is because it is an absolute priority to get on with this trade deal," Ms Truss told reporters in Canberra.

"I would say months rather than years for it to be completed."

Commonwealth touted as answer to EU void

The Queen is the head of the Commonwealth, made up of 53 states and home to 2.4 billion people. ( Pool via AP: Dominic Lipinski )

Heightened trade with the Commonwealth has been touted by some Brexiteers as one way for Britain to reduce the economic impact of a no-deal Brexit.

The UK's Office for Budget Responsibility found a no-deal would shrink the UK's economy by 2 per cent in 2020.

It also found public borrowing costs would skyrocket by 30 billion pounds ($54.7 billion) from 2020–21.

Official data showed the GDP of the UK would sink by two percent following a no-deal Brexit. ( UK Office for Budget Responsibility )

The Commonwealth — a bloc of nations mostly comprised of states previously belonging to the British Empire — is made up of 53 states collectively home to 2.4 billion people.

Its combined GDP was estimated to be $15.2 trillion in 2017, and it is predicted to reach $19 trillion by 2020, according to Commonwealth data.

But over half of the bloc's member states are small developing states with populations under 1.5 million.

Advanced economies within the bloc, such as India, Australia, New Zealand and Canada, have been touted to fill the economic void Britain inherits after leaving the EU.

But in a March editorial for the Guardian, former Australian prime minister Kevin Rudd noted this plan fails to acknowledge the sheer scale of the forthcoming void.

"Much as any Australian, Canadian and New Zealand governments of whichever persuasion would do whatever they could to frame new free-trade agreements with the UK, the bottom line is that 65 million of us do not come within a bull's roar of Britain's adjacent market of 450 million Europeans," he wrote.

Australia is Britain's seventh-largest trading partner

Boris Johnson (right) and Scott Morrison (left) met on the sidelines of the G7 summit last month. ( Reuters: Neil Hall )

Two-way trade between Australia and Britain is worth $26.6 billion, according to Australian data.

Britain is Australia's seventh-largest trading partner, the data shows.

Australian Trade Minister Simon Birmingham said a deal with Britain would particularly benefit the country's agricultural sector, worth around $60 billion.

"As part of the EU, market access to Britain in terms of agricultural products has been limited," Mr Birmingham told reporters.

"This is something we will look to address."

Canberra said Australia's agricultural exports to Britain were hampered by EU rules. ( ABC News: Laura Beavis )

In February, now-UK Prime Minister Boris Johnson told reporters he had advocated for a common travel area between Britain and Australia akin to the free movement enjoyed by Australia and New Zealand.

But to execute that idea, the PM has to take the UK out of the EU on October 31, with or without a deal with the bloc.

While there had been a trade deal negotiated over years between Brussels and London by Mr Johnson's predecessor, Theresa May, that was defeated in the House of Commons three times.

Throughout Brexit trade deal negotiations, the deal's post-Brexit Irish border policy — known as the Irish backstop — has stymied the deal's progression through Westminster, as some MPs reject the idea in its entirety.

This would see Northern Ireland continuing to remain within the EU's single market until technology allows for frictionless trade and movement on the island of Ireland.

It is also designed to prevent hard border infrastructure that some fear would disturb the peace between British loyalists and Irish nationalists.

This month, Westminster passed a law that requires Mr Johnson to ask the EU for a three-month delay to Brexit if a deal is not approved by October 19.

ABC/Reuters