LONDON: Britain will apply to join a massive 11-nation free-trade bloc of Asia-Pacific countries, it announced Saturday, weeks after leaving the European single market with its departure from the EU.

International Trade Secretary Liz Truss will formally request Monday for Britain to join the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), a market representing half a billion people and roughly 13.5 percent of the global economy.

The CPTPP application will come one year after Britain left the European Union following more than forty years of membership -- and after five years of complex trade discussions.

British Prime Minister Boris Johnson said the potential new partnership would "bring enormous economic benefits for the people of Britain".

"Applying to be the first new country to join the CPTPP demonstrates our ambition to do business on the best terms with our friends and partners all over the world and be an enthusiastic champion of global free trade," he said.

Negotiations between the UK and the partnership -- which represents 11 Pacific Rim nations including Australia, Canada, Chile, Japan, Mexico and Vietnam -- are expected to start this year, the trade department said.

But opposition Labour party shadow international trade secretary Emily Thornberry questioned the lack of transparency surrounding the pact.

After five years of debate over Brexit trade agreements, she said people would question the British government's decision "to rush into joining another one on the other side of the world without any meaningful public consultation at all."

"At present, Liz Truss cannot even guarantee whether we would have the right to veto China's proposed accession if we join the bloc first," she said.

Truss said joining the CPTPP would offer "enormous opportunities".

She has touted joining as Britain made agreements with members such as Japan and Canada in the wake of Brexit, with British media reporting that CPTPP nations accounted for around eight percent of UK exports in 2019.

Truss said the deal will mean lower tariffs for car manufacturers and whisky producers, as well as "delivering quality jobs and greater prosperity for people here at home".

Karan Bilimoria, president of the UK's largest business lobby group the Confederation of British Industry (CBI), said the move marked a "new chapter for our independent trade policy".

"Membership of the bloc has the potential to deliver new opportunities for UK business across different sectors," he said.

The CPTPP was launched in 2019 to remove trade barriers among the 11 nations representing nearly 500 million consumers in the Asia-Pacific region in a bid to counter China's growing economic influence.

The partnership is an updated version of a giant deal originally backed by former US president Barack Obama.

The United States pulled out of the agreement under Donald Trump's presidency -- turning away from what he viewed as unfavourable multilateral deals -- but 11 countries eventually agreed to sign the new version.

Following Britain's definitive departure from the European Union after a one year transition period out of the European single market at the end of 2020, the UK has sought to advance the brand of "Global Britain" in 2021.

The UK holds the rotating presidency of the G7 in 2021 and takes over the presidency of the UN Security Council in February.