The 11 member nations of the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP) have agreed to begin the process that will allow the UK to join the group.
Japanese economy minister Yasutoshi Nishimura told reporters after a virtual meeting of officials from the countries that the addition of the UK to the agreement would strengthen economic ties and make the group equal in size to the EU in terms of overall GDP.
The 11 nations also said in a joint statement: "The commencement of an accession process with the United Kingdom and the potential expansion of the CPTPP will send a strong signal to our trading partners around the world of our commitment to support a free, fair, open, effective, inclusive and rules-based trading system."
Becoming part of the CPTPP has been a key trade goal of the UK following Brexit, with the government making a formal application to join at the start of February.
At the time, UK international trade secretary Liz Truss said membership would mean lower tariffs for car manufacturers and whisky distillers, as well as greater access to new markets for UK service providers.
The CPTPP aims to eliminate 95 percent of tariffs on trade between its members - Japan, Canada, Australia, Vietnam, New Zealand, Singapore, Mexico, Peru, Brunei, Chile and Malaysia - but does not create a single market or customs union.
Mr Nishimura said: "I think there's a big meaning to this from a strategic viewpoint of strengthening economic relations between Japan and the UK."
The UK signed its first new post-Brexit free trade agreement (FTA) with Japan earlier this year, which included a provision for the Asian nation to support the UK's membership of CPTPP.
It is expected that a similar FTA with Australia set to be signed later this month will further pave the way for the UK's membership of the group.