TOKYO, June 25 (Kyodo News) - Japan ratified on Friday the Regional Comprehensive Economic Partnership, a mega trade agreement also involving China, Australia and the Association of Southeast Asian Nations, the Foreign Ministry said.

Tokyo deposited its ratification instrument with the ASEAN Secretariat, making it the third member to do so toward the possible enforcement of the 15-nation RCEP by the end of the year.

The ASEAN Secretariat processes operating procedures on behalf of the pact whose members account for about 30 percent of the world's output, trade and population.

The Cabinet approved the accord Friday, completing Tokyo's necessary domestic procedures for the ratification. It will be Japan's first trade deal involving both China and South Korea -- its largest and third biggest trade partners.

"The deal will strengthen the link between Japan and the (Asia-Pacific) region, which is the world's growth center, and will contribute to Japan's economic growth when it comes into force," Economy, Trade and Industry Minister Hiroshi Kajiyama said at a press conference.

The Japanese government estimated earlier this year that the trade treaty could lift the gross domestic product of the world's third-largest economy by about 2.7 percent.

The pact, signed by 15 countries last November, will enter into effect 60 days after it is ratified by at least six ASEAN members and three other signatory countries. Among the signatories, Singapore and China have completed ratification procedures.

The RCEP groups the 10 ASEAN states -- Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam -- as well as Australia, China, Japan, New Zealand and South Korea.