Taiwan has applied to join a major trans-Pacific trade deal, officials confirmed Thursday, days after China said it also wanted to become a member of the agreement.

The announcement was welcomed by Japan but could rile Beijing which tries to keep Taiwan isolated on the world stage.

Signed by 11 Asia-Pacific countries in 2018, the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP) is the region's biggest free-trade pact and accounts for around 13.5 percent of the global economy.

"Taiwan can't be left out in the world and has to integrate into the regional economy," cabinet spokesman Lo Ping-cheng told reporters.

Tokyo responded favourably to the announcement.

"Japan welcomes Taiwan's application to join the Trans-Pacific Partnership," Japanese foreign minister Toshimitsu Motegi told reporters in New York.

Negotiations for the sweeping trade deal were initially led by the United States as a way to increase its influence in the Asia-Pacific region.

It was also designed to keep China, which has its own regional trade deal, locked out.

But former US president Donald Trump, who disdained multilateral agreements, pulled out of the deal in 2017.

The CPTPP is the successor to those negotiations and includes Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, Peru, New Zealand, Singapore and Vietnam.

Taiwan had been lobbying to join the pact for years but Thursday's application made it official.

The island's announcement came less than a week after China said it had also formally applied to join.

Those hoping to join, such as Britain, must have the unanimous support of all the pact's member countries.

China's application comes at a time when Beijing is feuding with a host of western nations.

On Thursday, Australia said China must end a freeze on contact with senior Australian politicians if it hopes to sign up.

Taiwan's application will likely be opposed by Beijing, which views the self-ruled democratic island as its own territory and has vowed to one day seize it, by force if necessary.

China's authoritarian leaders baulk at any international relations with Taiwan.

They have ramped up economic, military and diplomatic pressure on the island since the 2016 election of President Tsai Ing-wen who views Taiwan as a sovereign nation.

All of the CPTPP members have official diplomatic relations with Beijing, not Taipei.

But China's growing threats towards Taiwan have generated international sympathy for the island among western powers.

John Deng, Taipei's lead trade negotiator, told reporters on Thursday that he expected Chinese opposition to Taiwan's inclusion.

But he portrayed Taiwan as a more reliable free-trade partner.

"We have the foundation of democracy and the rule of law so all our regulations are transparent and we respect private properties," he said.